LTQ does not have a wikipedia page so I will check elsewhere. In the meantime, I found another reason to just say no to beans – osteolathyrism aka odoratism, which is a form of the disease Lathyrism. Wikipedia says: The disease results from the ingestion of Lathyrus odoratus seeds (sweet peas) from the family Fabaceae (legumes). The toxin found in the sweet peas is (beta-aminopropionitrile), which affects the linking of collagen, a protein of connective tissues. The condition results in damage to bone and mesenchymal connective tissues. Osteolathyrism occurs in people in combination with neurolathyrism and angiolathyrism in areas where famine demands reliance on a crop with known detrimental effects. It occurs in cattle and horses with diets overreliant upon the grass pea. Prominent symptoms include skeletal deformities and bone pain. Disorders that are clinically similar to Laythyrism are konzo (an epidemic paralytic disease occurring among hunger-stricken rural populations in Africa where a diet dominated by insufficiently processed cassava results in simultaneous malnutrition and high dietary cyanide intake – “konzo” means “tied legs” in the Yaka language in Southwestern DR Congo) and Lytico-bodig disease aka Guam disease, or amyotrophic lateral sclerosis-parkinsonism-dementia (ALS-PDC). Another page says Oxalyldiaminopropionic acid (ODAP) is a structural analogue of the neurotransmitter glutamate found in the grass pea Lathyrus sativus. It is the neurotoxin responsible for the motor neuron degeneration syndrome lathyrism and yet another page points to both of these poisons, so I’m going to put the information in a couple of posts and move along. Osteolathyrism is mentioned at the Lysyl oxidase page among others.

Lysine tyrosylquinone (LTQ) has been identified as the active site cofactor in lysyl oxidase.

• Wang SX, Mure M, Medzihradszky KF, Burlingame AL, Brown DE, Dooley DM, Smith AJ, Kagan HM, Klinman JP. A crosslinked cofactor in lysyl oxidase: redox function for amino acid side chains. Science. 1996 Aug 23;273(5278):1078-84. doi: 10.1126/science.273.5278.1078. PMID: 8688089.
• Wang SX, Nakamura N, Mure M, Klinman JP, Sanders-Loehr J. Characterization of the native lysine tyrosylquinone cofactor in lysyl oxidase by Raman spectroscopy. J Biol Chem. 1997 Nov 14;272(46):28841-4. doi: 10.1074/jbc.272.46.28841. PMID: 9360949.
• Mure M, Wang SX, Klinman JP. Synthesis and characterization of model compounds of the lysine tyrosyl quinone cofactor of lysyl oxidase. J Am Chem Soc. 2003 May 21;125(20):6113-25. doi: 10.1021/ja0214274. PMID: 12785842.

The structure is derived from the crosslinking of the ε-amino group of a lysine residue with the modified side chain of a non-proximal tyrosyl residue. LTQ biogenesis is autocatalytic, requiring only the precursor protein, copper, and oxygen.

• Bollinger JA, Brown DE, Dooley DM. The Formation of lysine tyrosylquinone (LTQ) is a self-processing reaction. Expression and characterization of a Drosophila lysyl oxidase. Biochemistry. 2005 Sep 6;44(35):11708-14. doi: 10.1021/bi0504310. PMID: 16128571.

The LTQ cofactor is unique among quinones due to its ortho/benzoquinone structure and neutral charge under physiological pH. This can be contrasted with the similar ubiquitous quinocofactor TPQ, which exists as a negatively charged structure under physiological conditions and includes ortho/para-carbonyl resonance functionality.

• ^{Wang SX, Nakamura N, Mure M, Klinman JP, Sanders-Loehr J (Nov 1997). “Characterization of the native lysine tyrosylquinone cofactor in lysyl oxidase by Raman spectroscopy”. The Journal of Biological Chemistry. 272 (46): 28841–4. doi:10.1074/jbc.272.46.28841. PMID 9360949.}

LTQ is crucial in LOX-catalyzed conversion of lysine residues to α-aminoadipidic-δ-semialdehydes, generally referred to as allysines.

• ^{Bedell-Hogan D, Trackman P, Abrams W, Rosenbloom J, Kagan H (May 1993). “Oxidation, cross-linking, and insolubilization of recombinant tropoelastin by purified lysyl oxidase”. The Journal of Biological Chemistry. 268 (14): 10345–50. doi:10.1016/S0021-9258(18)82207-4. PMID 8098038.}

The mechanism of lysyl oxidase occurs via modification of the ε-amino group of a lysine side chain. The enzyme falls into the category of quinone-containing copper amine oxidases, and the reaction is highly dependent on the cofactor lysyl tyrosylquinone (LTQ). In the oxidation of lysine, the ε-amine is first converted to a Schiff base via reaction with LTQ. While LTQ is still bound to the substrate, rate-limiting removal of the ε-proton yields an imine intermediate. Subsequent hydrolysis of the imine leads to release of the aldehyde product, allysine. Molecular oxygen and the copper ion are utilized to reoxidize the cofactor and yield another imine, producing hydrogen peroxide as a side product. Additional hydrolysis releases ammonia and the original cofactor, completing the catalytic cycle.

• ^{Gacheru SN, Trackman PC, Shah MA, O’Gara CY, Spacciapoli P, Greenaway FT, Kagan HM (Nov 1990). “Structural and catalytic properties of copper in lysyl oxidase”. The Journal of Biological Chemistry. 265 (31): 19022–7. doi:10.1016/0162-0134(89)84532-5. PMID 1977746.}
• Akagawa M, Suyama K (Feb 2001). “Characterization of a model compound for the lysine tyrosylquinone cofactor of lysyl oxidase”. Biochemical and Biophysical Research Communications. 281 (1): 193–9. doi:10.1006/bbrc.2001.4315. PMID 11178979.

Lysyl oxidase (LOX), also known as protein-lysine 6-oxidase, is an enzyme that, in humans, is encoded by the LOXgene.

• “Entrez Gene: LOX lysyl oxidase”.
• Hämäläinen ER, Jones TA, Sheer D, Taskinen K, Pihlajaniemi T, Kivirikko KI (Nov 1991). “Molecular cloning of human lysyl oxidase and assignment of the gene to chromosome 5q23.3-31.2”. Genomics. 11 (3): 508–16. doi:10.1016/0888-7543(91)90057-L. PMID 1685472.

It catalyzes the conversion of lysine molecules into highly reactive aldehydes that form cross-links in extracellular matrix proteins. Its inhibition can cause osteolathyrism, but, at the same time, its upregulation by tumor cells may promote metastasis of the existing tumor, causing it to become malignant and cancerous.

Osteolathyrism, sometimes referred to as odoratism, is a form of the disease Lathyrism. The disease results from the ingestion of Lathyrus odoratus seeds (sweet peas). The toxin found in the sweet peas is (beta-aminopropionitrile), which affects the linking of collagen, a protein of connective tissues. The condition results in damage to bone and mesenchymal connective tissues. Osteolathyrism occurs in people in combination with neurolathyrism and angiolathyrism in areas where famine demands reliance on a crop with known detrimental effects. It occurs in cattle and horses with diets overreliant upon the grass pea. Prominent symptoms include skeletal deformities and bone pain.

• Dasler, Waldemar; Mosby, Mildred (November 1954). “Incisor Ash Versus Femur Ash in Sweet Pea Lathyrism (Odoratism)”. The Journal of Nutrition. 54 (3): 397–402. doi:10.1093/jn/54.3.397. PMID 13212476.
• Haque, Abdul; Hossain, Muffazal; Lambien, Fernand; Bell, E. Arthur (May 2006). “Evidence of Osteolathyrism among patients suffering from Neurolathyrism in Bangladesh”. Natural Toxins. 5 (1): 43–6. doi:10.1002/(SICI)(1997)5:1<43::AID-NT7>3.0.CO;2-M. PMID 9086459.
• Rosenthal, Gerald (2003). “Toxic Constituents and their Related Metabolites”. Plant Nonprotein Amino and Imino Acids: Biological, Biochemical, and Toxicological Properties. Elsevier. ISBN 9780323157742.

Lysyl oxidase is an important enzyme for the creation of crosslinks between collagen triple-helices in connective tissue. By oxidizing the terminal amino group of lysine, an aldehyde is created. This aldehyde can undergo several reactions with neighboring aldehydes or amines to create strong covalent cross-links between collagen tertiary structures in bone and cartilage. The main product of these reactions is the aldimine compound dehydrohydroxylysinonorleucine.

• Bailey, A. J.; Peach, C. M. (1971). “The chemistry of the collagen cross-links. The absence of reduction of dehydrolysinonorleucine and dehydrohydroxylysinonorleucine in vivo”. The Biochemical Journal. 121 (2): 257–9. doi:10.1042/bj1210257. PMC 1176564. PMID 5117030.

This unique crosslink can be formed by the Schiff base mechanism in which the lone pair of electrons on a primary amine react with the carbonyl carbon of an aldehyde. Other crosslinks include the formation of an α,β-unsaturated ketone via aldol condensation and hydroxylysinonorleucine.

If these crosslinks are not formed, as in the case of osteolathyrism, the synthesis of strong mesenchymal and mesodermal tissue is inhibited. Symptoms of osteolathyrism include weakness and fragility of connective tissue (i.e., skin, bones, and blood vessels (angiolathyrism) and the paralysis of the lower extremities associated with neurolathyrism. For these reasons, compounds containing lathyrogens should be avoided during pregnancy and growth of a child. Prevention of osteolathyrism can be achieved with a cessation of L. sativus consumption.