The unambiguous study of homocysteine metabolism requires a source of [355]homocysteine completely free from contaminating [35S]methionine. Until now, such a reagent has not been readily available. Homocysteine is an important metabolite involved in methionine, cysteine and methylation metabolism. Homocysteine can be methylated to form methionine with either 5-methyltetrahydrofolate [1] or beta...

We aimed to investigate the vascular effects of hyperhomocysteinemia (HHcy) on carotid arteries from young and adult rats. With this purpose young and adult rats received a solution of DL-homocysteine-thiolactone (1 g/kg body weight/day) in the drinking water for 7, 14 and 28 days. Increase on plasma homocysteine occurred in young and adult rats treated with DL-homocysteine-thiolactone in all p...

The formation of homocysteine thiolactone (HcyTl) from homocysteine occurs in all examined so far organisms including bacteria, yeast, and humans. Protein N-homocysteinylation at the ε-amino group of lysine is an adverse result of HcyTl accumulation. Since tagging of proteins by ubiquitination before their proteasomal degradation takes place at the same residue, we wondered how N-homocysteinyla...

influence of folic acid on the cns is still unclear. folate has a neuroprotective effect, while on the other hand excess folate can exacerbate seizures in epileptics. the aim of the present study was to examine the effect of subchronic administration of folic acid on behavioural and electroencephalographic (eeg) characteristics of dl homocysteine thiolactone induced seizures in adult rats. t...

All living organisms conduct protein synthesis with a high degree of accuracy maintained in the transmission and flow of information from a gene to protein product. One crucial 'quality control' point in maintaining a high level of accuracy is the selectivity by which aminoacyl-tRNA synthetases furnish correctly activated amino acids, attached to tRNA species, as the building blocks for growing...

The reactions of a-chymotrypsinogen with carbon disulfide and with 0-methylisourea have been reported from this laboratory previously (1,2). The present report concerns the reaction of this protein with a new acylating agent, N-acetyl-nn-homocysteine thiolactone. The use of the thiolactone for the introduction of sulhydryl groups into proteins was fist suggested by Benesch and Benesch (3,4) who...