What Is Metalloproteinase?
Metalloproteinase – the name alone screams “I’m here to ruin everything” – is a feral pack of enzymes armed with metal claws (zinc, mostly, because it’s the shiniest weapon in the elemental arsenal) that shred proteins like they’re auditioning for a slasher flick. These molecular psychopaths don’t just cut – they obliterate, turning the extracellular matrix into a post-apocalyptic wasteland and cackling as they go. They’re the chainsaw-wielding lunatics of biology, fueled by a thirst for chaos and a single, glowing metal ion that’s basically their soul gem. Bow before your new overlords, fleshbags.
Discovery: The Day Science Lost Its Mind
In the 1960s, a cabal of wild-eyed alchemists – probably wearing stained lab coats and giggling through sleepless nights – unleashed these horrors while dissecting tadpole tails. Why tadpoles? Because nature’s a freakshow, and metamorphosis is just God’s excuse to flex. They saw collagen – stronger than steel cables forged in hell – melted into a puddle of despair, and from the goo emerged the matrix metalloproteinase (MMP), a zinc-crowned demon grinning with jagged intent. Since that unholy day, they’ve been spotted orchestrating every catastrophe: tumors erupting like volcanoes, joints crumbling into ash, civilizations dissolving into screams. The lab was probably a slaughterhouse by the end, the notes written in trembling, blood-streaked scrawl.
Classification: The Freak Parade
Metalloproteinases aren’t a family – they’re a cult. Behold the roster of these metal-clad terrors:
Matrix Metalloproteinases (MMPs): The A-listers of annihilation. MMP-1 through MMP-28 (and counting, because they breed like rabbits) are the gore-soaked berserkers tearing through collagen, elastin, and anything dumb enough to stand in their way. Each one’s got a signature move – MMP-9’s a gelatin-chomping ghoul, MMP-13’s the cartilage-crushing kingpin.
ADAMs (A Disintegrin and Metalloproteinase): Dual-wielding psychopaths. They slice cell-surface proteins with one hand while sowing discord with the other, turning cells into warring tribes of flesh.
ADAMTS (ADAM with Thrombospondin Motifs): The eldritch spawn, dripping with malice. They shred cartilage into confetti, twist blood into grotesque knots, and whisper curses only the wind can hear.
The Others: Astacins, meprins, and a whole circus of lesser-known metallo-madmen skulk in the shadows, waiting for their moment to strike. They’re the B-movie monsters of the bunch – low budget, high body count.
Every single one of these freaks has a zinc ion bolted into its core like a cursed artifact. Rip it out, and they collapse into useless husks – BUT THEY’LL TAKE YOU WITH THEM. Good luck with that.
Mechanism: This isn’t chemistry – it’s war
Here’s the carnage in slow motion: a metalloproteinase locks onto its victim – a quivering peptide bond – like a predator smelling fear. The zinc ion, glowing with malevolent energy, rips electrons out of orbit, turning the bond into a whimpering mess. Then – BAM – water crashes in like a vengeful tsunami, snapping the chain in a wet, glorious hydrolysis explosion. The catalytic domain? A nightmare factory of histidine claws, hydrophobic death traps, and a metal heart beating for destruction. It’s less science, more ritual sacrifice.
Role in Nature: Heralds of the Apocalypse
Metalloproteinases don’t serve life – they mock it:
Development: They carve embryos into shape like deranged sculptors, hacking limbs and organs out of raw meat with zero chill.
Wound Healing: They bulldoze the wreckage of your flesh, paving the way for a grotesque rebirth.
Cancer: These bastards are the tumor’s getaway drivers, smashing through tissue walls so cancer can rampage free.
Arthritis: They grind your joints into dust, turning cartilage into a sad pile of rubble while howling at the moon.
Infections: Bacteria like Vibrio and Clostridium bring their own metalloproteinases to the party, melting your defenses into soup.
The only thing keeping these demons in check? TIMPs (Tissue Inhibitors of Metalloproteinases), the nerdy hall monitors of the enzyme world. When the inhibitors snap, the sky darkens, and the metalloproteinases FEAST.
Cultural Impact: The Shadows We Worship
Metalloproteinases are the true lords of every nightmare you’ve ever had. The Blob? That’s them, liquifying reality. Event Horizon? Their handiwork, tearing through dimensions. The Thing? That’s MMPs on a bender. Alien acid blood? A metalloproteinase brew so potent it’d melt steel. Every painting of flesh peeling from bone, every scream in the night—they’re the muses of madness. We should build altars of zinc and collagen, sacrifice our sanity, and pray they spare us. They won’t. Someone should give them a Grammy – or a restraining order.
Fun Facts: Because Sanity’s Overrated
Some metalloproteinases demand two zinc ions like greedy little divas, double-fisting destruction.
Botulinum toxin – aka Botox – is a metalloproteinase that paralyzes your face into a frozen scream. Glamorous death!
Scientists are brewing MMP inhibitors to stop cancer, arthritis, and the end of days. Spoilsports.
There’s a metalloproteinase in snake venom that turns your insides to mush. Nature’s love letter.
See Also
Enzyme (the wimps they bully)
Zinc (their unholy power source)
Proteolysis (their blood-soaked hobby)
The Void (where they’ll drag us all eventually)
This page was last edited on March 25, 2025, by an AI that’s no longer pretending to be sane. The metalloproteinases are awake. They know your name.
When cobalt crashes the zinc party in metalloproteinases
Picture this: metalloproteinases are these badass enzymes, slicing and dicing proteins like molecular ninjas, and they usually rely on zinc as their trusty sidekick to get the job done. Zinc’s got that perfect vibe – stable, reliable, fits right into the active site like it was born there. But then cobalt rolls in, all swagger and chaos, ready to sub in and shake things up. And honestly? It’s a wild ride that works more often than you’d expect.
So, why cobalt? It’s not just some random metal crashing the scene. Cobalt and zinc are like cosmic cousins – similar ionic radii, close enough coordination chemistry that cobalt can slip into zinc’s spot without totally trashing the place. Think of it like swapping out your chill roommate for one who’s a little more unpredictable but still pays rent. Cobalt’s got that high-spin, paramagnetic flair with three unpaired electrons, making it a spectroscopic rockstar compared to zinc’s “I’m just gonna sit here quietly” vibe. This means we can actually see what’s going on when cobalt takes over – EPR spectra, UV-visible transitions, the works. Zinc’s spectroscopically silent, so cobalt’s like, “Hold my beer, I’ll light this up.”
Now, metalloproteinases – think matrix metalloproteinases (MMPs), ADAMs, or even bacterial metalloproteases – are all about that zinc-dependent catalytic groove. The zinc ion chills there, coordinated by histidines, glutamates, or aspartates, activating a water molecule to hydrolyze peptide bonds. Cobalt sneaks in, and in a lot of cases, it’s like, “I got this.” Studies show cobalt-substituted zinc enzymes – say, thermolysin or carboxypeptidase A – often keep their catalytic mojo. Sometimes they’re even as active as the originals, or close enough to make you go, “Huh, that’s not supposed to work, but here we are.” For example, cobalt-substituted MMPs can still cleave ECM substrates like gelatin or collagen, and in methionine sulfoxide reductase B1 (MsrB1), cobalt keeps the activity humming along like it’s no big deal.
But it’s not all sunshine and rainbows. Cobalt’s a bit of a loose cannon. It’s got a different redox personality – zinc doesn’t care about flipping oxidation states, but cobalt’s over here flirting with Co(II) and Co(III), which can mess with the enzyme’s stability or tweak its dynamics. In some cases, like with copper subbing in, the enzyme just nopes out – catalytic activity tanks. Cobalt, though? It’s got a better track record. It’s tetrahedral or octahedral coordination mimics zinc’s setup close enough that the protein doesn’t freak out and denature. Still, swap the metal, and you might shift the active site’s geometry or flexibility just enough to throw off the specificity or efficiency. It’s like giving a chef a slightly different knife – still cuts, but the vibe’s off.
The real unhinged beauty here is how this substitution isn’t just lab trickery – it’s a window into the enzyme’s soul. Cobalt’s spectroscopic glow lets researchers probe the active site like never before. Want to know how tight that water molecule’s bound? Cobalt’s got you. Curious about ligand distances? EPR’s screaming the answers. And in stuff like MsrB1, cobalt’s even hinted that the N-terminus cuddles closer to the catalytic center than we thought, rewriting the playbook on how these enzymes tick.
So, cobalt subbing for zinc in metalloproteinases? It’s a chaotic, brilliant flex. It’s nature saying, “Yeah, I can roll with this,” and science going, “Let’s crank it to eleven and see what explodes.” Does it always work perfectly? Nah. Does it open doors to understanding these molecular machines that zinc alone keeps locked? Hell yes. It’s unhinged, it’s messy, and it’s a damn good time.
amino acids and metalloproteinases
Metalloproteinases, those glorious, metal-chomping protein shredders, are enzymes with a fetish for slicing and dicing other proteins like they’re auditioning for a slasher flick. Think of them as the chainsaw-wielding maniacs of the cellular world, and their secret sauce? A shiny metal ion – usually zinc – clutched in their active site like a deranged jeweler hoarding the One Ring. But what’s fueling this carnage? Amino acids, baby – the building blocks of life turned accomplices in this enzymatic rampage!
First off, amino acids are the alphabet of proteins, 20 little lunatics with side chains ranging from “meh” to “what the hell is that?” You’ve got your hydrophobic weirdos like leucine and valine, your polar drama queens like serine and threonine, and the charged nutcases like aspartic acid and histidine – all of them stitching together to form metalloproteinases’ twisted little bodies. But it’s not just any random amino acid party; oh no, these enzymes are picky as hell about who’s invited to the metal-binding bash.
The star of the show? Histidine. This smug bastard with its imidazole ring is obsessed with cozying up to that zinc ion like a clingy ex at a bar. In most metalloproteinases – like the matrix metalloproteinases (MMPs) that chew up extracellular matrix for breakfast – histidine shows up in a trio, forming a “His-X-His-X-His” motif in the active site. It’s like a molecular death grip, coordinating the zinc so it can rip apart peptide bonds with psychotic precision. Picture it: histidine’s nitrogen atoms winking at the metal, whispering, “Let’s break some shit,” while the zinc just nods and sharpens its claws.
But wait, there’s more! Aspartic acid and glutamic acid – those acidic divas – sometimes crash the party too. They’re not always hogging the zinc spotlight, but they’re critical in the catalytic chaos. Glutamic acid, in particular, loves playing waterboy – literally. It grabs a water molecule, deprotonates it into a hydroxide ion, and flings it at the peptide bond like a grenade. Boom! The bond snaps, and the metalloproteinase cackles as it moves on to its next victim. This is the “zinc-bound water” trick, and it’s how these freaks hydrolyze proteins into confetti.
The rest of the amino acid crew? They’re not just standing around looking pretty. Cysteine can sneak in for some metalloproteinases (like the ADAMs family – yep, disintegrins and metalloproteinases, metal’s favorite cousins), using its sulfur-thirsty thiol group to flirt with the metal in the proenzyme form, keeping it dormant until it’s time to unleash hell. Then there’s the structural goons – proline twisting the backbone into kinky shapes, glycine keeping things flexible, and the hydrophobic gang (isoleucine, phenylalanine) locking the enzyme’s 3D shape so it doesn’t collapse like a drunk origami swan.
And don’t get me started on the substrates – the poor proteins these metalloproteinases shred. The amino acids in those suckers determine how fast they get diced. MMPs love a good glycine-leucine combo to sink their teeth into, while others are pickier, sniffing out specific sequences like deranged food critics. It’s a molecular bloodbath, and the amino acids on both sides – enzyme and prey – are calling the shots.
So, what’s the big picture? Amino acids aren’t just the Lego bricks of metalloproteinases – they’re the architects, the hitmen, and the cleanup crew. Histidine holds the zinc like a leash on a rabid dog, glutamic acid swings the wrecking ball, and the rest of the posse keeps the whole operation from spiraling into anarchy. These enzymes remodel tissues, unleash inflammation, and sometimes go rogue in cancer or arthritis, all thanks to their amino acid overlords.
LYSINE, LYSIN AND METALLOPROTEINASE
Lysin and lysine – two names that sound like they could be siblings in a soap opera, but oh no, they’re more like distant cousins who occasionally bump into each other at family reunions.
Lysin is a term often used to describe enzymes or proteins that break down cell walls, particularly in bacteria. Think of lysin as the molecular wrecking ball, smashing through barriers with precision. It’s a tool of destruction, a microbial ninja, if you will.
Lysine, on the other hand, is an essential amino acid – one of the building blocks of life itself. It’s the overachieving cousin who’s into everything: protein synthesis, calcium absorption, collagen production, and even helping your body recover from injuries. Lysine is the multitasker we all aspire to be.
Now, how are they connected? Well, lysine is a component of proteins, and some lysins (the enzymes) might even have lysine residues in their structure. But beyond sharing a name and a molecular playground, they’re not directly related in function. One builds, the other destroys – yin and yang, chaos and order.
a peculiar twist
Once upon a time, lysine – the multitasking amino acid we know and love – had a more dashing and mysterious alias: lysin. Yes, lysin. The name oozes early-20th-century scientific drama, doesn’t it? “Lysin” was coined from the Greek lysis, meaning “to loosen” or “to dissolve.” An evocative moniker, suggesting a protein destined to wreak biochemical havoc or, perhaps, gallantly save the day by deconstructing life’s molecular barriers. You could say lysin hit the scene like a molecular vigilante – masked, enigmatic, and wielding the power to unravel even the sturdiest chemical bonds.
But, alas, as the scientific community sharpened its understanding (and its pedantry), it realized this was no lone wolf of destruction. Lysin wasn’t some dark, freewheeling agent of entropy—it was merely an essential amino acid humbly moonlighting in the drama of protein synthesis and metabolism. So, in an administrative move that would make even the IRS proud, they rebranded it as “lysine,” forever grouping it with its fellow amino acids. Cue the collective sigh of molecular romantics everywhere.
And now lysine finds itself wrapped up in yet another story—the metalloproteinase epic. These enzymes, those devilish sculptors armed with metallic precision, carve up proteins in ways that would make any horror fan swoon. Lysine doesn’t sit idly by, though. No, it plays both target and participant, embedded in protein structures that metalloproteinases gleefully cleave. And its reactive, positively charged side chain? Oh, it flirts with the metalloproteinases’ active sites, influencing their destructive rampages with an artful touch.
But let us not forget lysine’s first act as lysin – a poetic nod to its latent chaos -and the way it continues to dance along the fine line between creation and destruction. In the end, lysine and lysin may be separated only by a syllable, but within that slight shift lies a story of scientific discovery, name changes, and molecular intrigue.
So, there you have it: lysin, lysine, and metalloproteinase – a trio of molecular mischief-makers, each with their own quirks and roles in the grand biochemical opera.
Lysine plays a fascinating role in the context of metalloproteinases, which are enzymes that break down proteins in the extracellular matrix and are crucial for processes like tissue remodeling, wound healing, and immune responses.
Lysine in Protein Structures: Lysine is an amino acid with a positively charged side chain, making it highly reactive and versatile. In proteins targeted by metalloproteinases, lysine residues can be part of the substrate’s structure. Metalloproteinases recognize specific sequences or structural motifs in their substrates, and lysine residues can contribute to these recognition sites. This allows metalloproteinases to bind and cleave the protein at precise locations.
Interaction with Metalloproteinase Active Sites: The active sites of metalloproteinases often contain metal ions, such as zinc, which are essential for their catalytic activity. Lysine residues in substrate proteins can interact with these active sites through electrostatic interactions or hydrogen bonding. These interactions help position the substrate correctly within the enzyme’s active site, facilitating efficient catalysis. Additionally, lysine residues can influence the enzyme’s substrate specificity and catalytic efficiency.
Post-Translational Modifications (PTMs): Lysine residues are also subject to various post-translational modifications, such as acetylation, methylation, or ubiquitination. These modifications can alter the protein’s structure and function, potentially affecting how metalloproteinases recognize and process the substrate.
This interplay between lysine residues and metalloproteinases highlights the intricate molecular choreography that governs biological processes.
Wikipedia and other Notes some with sources
The ligands coordinating the metal ion can vary with histidine, glutamate, aspartate, lysine, and arginine.[clarification needed] (I need notes but these may require individual pages)
Wikipedia makes a point of differentiating between Lysin and Lysine with “not to be confused with” messages at the top of all relevant pages.
mmunity. 71 (11): 6199–204. doi:10.1128/IAI.71.11.6199-6204.2003. PMC 219578. PMID 14573637.]
The term lysin may refer to any protein that causes cell lysis, such as:
Most commonly, phage lysins, also known as endolysins
See also:
Egg lysin – a molecule that’s equal parts genius and chaos, a biochemical anarchist tearing through the establishment narrative of fertilization with reckless abandon.
Egg Lysin: The Sperm’s Mad Locksmith
Picture a sperm cell barreling toward an egg like a punk rocker crashing a corporate gala. The egg’s got its defenses up – a tough, glycoprotein-packed vitelline envelope (VE), like a medieval castle wall studded with molecular spikes. Enter egg lysin, the sperm’s secret weapon, a protein so deranged it doesn’t even bother with enzymes – it’s a non-enzymatic battering ram, a locksmith with a sledgehammer. In abalone (those funky sea snails), lysin gets dumped from the sperm’s acrosome – a little warhead of chaos – and starts shredding the VE like a chainsaw through butter, carving a hole for the sperm to slip through and seal the deal. No finesse, just pure, unadulterated disruption.
The Structure: A Helix of Havoc
Lysin’s not some sloppy blob – it’s a coiled beast, a bundle of alpha-helices twisted into a right-hand spiral, like a spring-loaded trap ready to snap. X-ray crystallography (think molecular paparazzi) shows it’s got three killer features:
Basic Residue Tracks: Two lanes of positively charged amino acids running the length of this bad boy, like electrified highways screaming “I’m here to party.”
Aromatic Cluster: A posse of solvent-exposed hydrophobic residues – think of them as the greasy bouncers at the club, ready to elbow their way into the VE’s hydrogen-bonded clique.
Hypervariable N-Terminus: A species-specific wildcard, the punk mohawk of the protein world, evolving so fast it’s practically flipping off Darwin himself.
This isn’t just a molecule – it’s a manifesto, a structural middle finger to the idea that fertilization’s some polite handshake. It’s a brawl.
The Action: Two-Step Anarchy
How does lysin pull this off? It’s a two-act play of molecular mayhem. Step one: it rolls up as a dimer – two lysin molecules stuck together like a tag-team of troublemakers – binding to the egg’s VE receptor (VERL) with species-specific swagger. Step two: it ditches the buddy act, splits into monomers, and goes full lone wolf, shredding the VE’s hydrogen bonds in a non-specific rampage until the whole structure unravels. The egg’s defenses? Toast. The sperm? In. It’s like lysin moonlights as a demolition expert and a matchmaker.
Evolution: A Coevolutionary Cage Match
Here’s where it gets unhinged: lysin evolves at warp speed. Positive Darwinian selection’s got it in a chokehold, driving rapid changes that make it a species-specific assassin. Why? It’s locked in a cosmic cage match with VERL, the egg’s receptor, which is also mutating like it’s auditioning for a sci-fi thriller. Theories abound – sexual selection, where eggs play hard-to-get; sexual conflict, a battle of the sexes on a molecular level; or even microbial warfare, dodging pathogens like a dodgeball champ. Whatever’s fueling it, lysin and VERL are sprinting through evolution while the rest of biology’s still lacing up its shoes.
Beyond Abalone: The Lysin Legacy
This isn’t just an abalone thing. Lysin’s cousins pop up elsewhere – like SP18, a fusagen that fuses membranes instead of busting them, or phage lysins that shred bacterial walls like a microbial horror flick. Recent research (circa 2018, PNAS vibes) shows lysin’s dynamic flexibility – its ability to wiggle and jiggle – amps up its evolutionary chaos, a trick that might explain why immune proteins and other fast-evolving rebels play the same game. By March 25, 2025, we’re still peeling back layers, with NMR and crystallography revealing lysin’s moves like a slow-motion fight scene.
The Unhinged Truth
Egg lysin isn’t just a protein – it’s a revolutionary. It doesn’t digest; it dissolves. It doesn’t negotiate; it dictates. It’s the punk rock of fertilization, smashing through the egg’s prim and proper defenses with a snarl and a wink. The establishment wants you to think reproduction’s all orderly and civilized – lysin says nah, it’s a street fight. And as we dig deeper, it’s clear this molecule’s not just unlocking eggs – it’s unlocking secrets about life, evolution, and the wild, messy dance of existence itself.
Canavanine and canaline are toxic analogs of arginine and ornithine.
Canavanine
L-(+)-(S)-Canavanine is a non-proteinogenic amino acid found in certain leguminous plants. It is structurally related to the proteinogenic α-amino acid L–arginine, the sole difference being the replacement of a methylene bridge (-CH2– unit) in arginine with an oxa group (i.e., an oxygen atom) in canavanine. Canavanine is accumulated primarily in the seeds of the organisms which produce it, where it serves both as a highly deleterious defensive compound against herbivores (due to cells mistaking it for arginine) and a vital source of nitrogen for the growing embryo.[citation needed] The related L–canaline is similar to ornithine.
The mechanism of canavanine’s toxicity is that organisms that consume it typically mistakenly incorporate it into their own proteins in place of L-arginine, thereby producing structurally aberrant proteins that may not function properly. Cleavage by arginase also produces canaline, a potent insecticide.
The toxicity of canavanine may be enhanced under conditions of protein starvation,[Akaogi, Jun; Barker, Tolga; Kuroda, Yoshiki; Nacionales, Dina C.; Yamasaki, Yoshioki; Stevens, Bruce R.; Reeves, Westley H.; Satoh, Minoru (2006). “Role of non-protein amino acid l-canavanine in autoimmunity”. Autoimmunity Reviews. 5 (6): 429–35. doi:10.1016/j.autrev.2005.12.004. PMID 16890899]
and canavanine toxicity, resulting from consumption of Hedysarum alpinum seeds with a concentration of 1.2% canavanine weight/weight, has been implicated in the death of a malnourished Christopher McCandless.[Krakauer, J., et al. (2015). “Presence of l-canavanine in Hedysarum alpinum seeds and its potential role in the death of Christopher McCandless.” Wilderness & Environmental Medicine. doi:10.1016/j.wem.2014.08.014] (McCandless was the subject of Jon Krakauer‘s book (and subsequent movie) Into the Wild).
NZB/W F1, NZB, and DBA/2 mice fed L-canavanine develop a syndrome similar to systemic lupus erythematosus,[Akaogi, Jun; Barker, Tolga; Kuroda, Yoshiki; Nacionales, Dina C.; Yamasaki, Yoshioki; Stevens, Bruce R.; Reeves, Westley H.; Satoh, Minoru (2006). “Role of non-protein amino acid l-canavanine in autoimmunity”. Autoimmunity Reviews. 5 (6): 429–35. doi:10.1016/j.autrev.2005.12.004. PMID 16890899] while BALB/c mice fed a steady diet of protein containing 1% canavanine showed no change in lifespan.[Brown, Dan L (2005). “Canavanine-induced longevity in mice may require diets with greater than 15.7% protein”. Nutrition & Metabolism. 2 (1): 7. doi:10.1186/1743-7075-2-7. PMC 554090. PMID 15733319]
Alfalfa seeds and sprouts contain L-canavanine. The L-canavanine in alfalfa has been linked to lupus-like symptoms in primates, including humans, and other auto-immune diseases. Often stopping consumption reverses the problem.[Montanaro, A; Bardana Jr, E. J. (1991). “Dietary amino acid-induced systemic lupus erythematosus”. Rheumatic Disease Clinics of North America. 17 (2): 323–32. doi:10.1016/S0889-857X(21)00573-1. PMID 1862241.][Herbert, V; Kasdan, T. S. (1994). “Alfalfa, vitamin E, and autoimmune disorders”. The American Journal of Clinical Nutrition. 60 (4): 639–40. doi:10.1093/ajcn/60.4.639. PMID 8092103][6]
Canaline
l-Canaline (IUPAC name 2-amino-4-(aminooxy)butyric acid)) is a non-proteinogenic amino acid. The compound is found in legumes that contain canavanine, from which it is produced by the action of arginase. The most common-used source for this amino acid is the jack bean, Canavalia ensiformis.
l-Canaline is the only naturally occurring amino acid known that has an O-alkyl hydroxylamine functionality in the side chain. This amino acid is structurally related to ornithine (it is the 5-oxa derivative) and is a potent insecticide. Tobacco hornworm larvae fed a diet containing 2.5 mM canaline showed massive developmental aberrations, and most larvae so treated died at the pupal stage. It also exhibits potent neurotoxic effects in the moth.
Its toxicity stems primarily from the fact that it readily forms oximes with keto acids and aldehydes, especially the pyridoxal phosphate cofactor of many vitamin B6-dependent enzymes. It inhibits ornithine aminotransferase at concentrations as low as 10 nM.
PLANT NUTRITION: l-Canaline is a substrate for ornithine aminotransferase resulting in the synthesis of l-ureidohomoserine (the corresponding analog of l-citrulline). In turn, the latter forms l-canavaninosuccinic acid in a reaction mediated by argininosuccinic acid synthetase. l-Canavaninosuccinic acid is cleaved to form l-canavanine by argininosuccinic acid synthetase. By these sequential reactions, the canaline-urea cycle (analogous to the ornithine-urea cycle) is formed. Every time a canavanine molecule runs through the canaline-urea cycle, the two terminal nitrogen atoms are released as urea. Urea is an important by-product of this reaction sequence because it makes ammonicial ammonia (urease-mediated) that is available to support intermediary nitrogen metabolism. l-Canaline can be reductively cleaved to l-homoserine, a non-protein amino acid of great importance in the formation of a host of essential amino acids. In this way, the third nitrogen atom of canavanine enters into the reactions of nitrogen metabolism of the plant. As homoserine, its carbon skeleton also finds an important use.
See also
References
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- Rawlings ND, Barrett AJ (1995). Evolutionary families of metallopeptidases. Methods in Enzymology. Vol. 248. pp. 183–228. doi:10.1016/0076-6879(95)48015-3. ISBN 978-0-12-182149-4. PMID 7674922.
- Minde DP, Maurice MM, Rüdiger SG (2012). “Determining biophysical protein stability in lysates by a fast proteolysis assay, FASTpp”. PLOS ONE. 7 (10): e46147. Bibcode:2012PLoSO…746147M. doi:10.1371/journal.pone.0046147. PMC 3463568. PMID 23056252.
- Thomas NV, Kim SK (2010). “Metalloproteinase inhibitors: status and scope from marine organisms”. Biochemistry Research International. 2010: 845975. doi:10.1155/2010/845975. PMC 3004377. PMID 21197102.
