4381 L-Homocystine Homocystine is the double-bonded form of homocysteine, but it occurs only transiently before being converted to the harmless cystathionine via a vitamin B6-dependent enzyme. Homocystine and homocysteine-cysteine mixed disulfide account for >98% of total homocysteine in plasma from healthy individuals. Oxidation of low-density lipoprotein (LDL) is thought to be a major factor in the pathophysiology of atherosclerosis. Elevated plasma homocysteine is an accepted risk factor for atherosclerosis, and may act through LDL oxidation, although this is controversial. However, the major thiol in plasma is cysteine, which is present at concentrations approximately 10 times greater than homocysteine; therefore homocystine in plasma is insignificant, and consequently homocystine is unlikely to influence LDL oxidation in vivo. Increasing evidence supports a role for an elevation of homocysteine in schizophrenia. It has been demonstrated that neural tube defects are related to a genetic defect in homocysteine metabolism. Sufficient intake of folic acid is believed to reduce this risk by enhancing methylation of homocysteine and its conversion to methionine, thereby compensating for this genetic defect. Plasma homocysteine levels are elevated when folate levels are in the lower half of the normal range. (A3414, A3415, A3416). 626-72-2 69382 C8H16N2O4S2 White powder. 300°C 0.2 mg/mL at 25°C No indication of carcinogenicity to humans (not listed by IARC). This is an endogenously produced metabolite found in the human body. It is used in metabolic reactions, catabolic reactions or waste generation. 2014-08-29T06:27:34Z 2026-04-02T23:59:27Z C01817 17485 true NC(CCSSCC[C@H](N)C(O)=O)C(O)=O C8H16N2O4S2 InChI=1S/C8H16N2O4S2/c9-5(7(11)12)1-3-15-16-4-2-6(10)8(13)14/h5-6H,1-4,9-10H2,(H,11,12)(H,13,14)/t5-,6?/m0/s1 ZTVZLYBCZNMWCF-ZBHICJROSA-N 268.354 268.05514839 Endogenous Solid HMDB00676 62590 CHEM003287 DTXSID001019905 NS00014871 126.64 64.38180000000001 26.91822397662728 9 6 4 1.8009555846997536 9.80244167200791 0 0 -4.15 -1.78 4.50e+00 g/l