betaine biosynthesis via glycine ..
Although flavins often function as noncovalently bound prosthetic groups, a growing number of flavoenzymes have been found to contain covalently bound flavin. This diverse group of enzymes perform a remarkable range of reactions, including ion pumping, antibiotic synthesis and metabolism of biogenic amines (–). Monomeric sarcosine oxidase (MSOX) is a prototypical member of a recently discovered family of amine-oxidizing enzymes that all contain covalently bound flavin (–). MSOX is an inducible bacterial enzyme that plays an important role in the catabolism of sarcosine (N-methylglycine), a common soil metabolite (). The enzyme is widely used in the clinical evaluation of renal function (). MSOX catalyzes the oxygen-dependent demethylation of sarcosine to yield glycine, formaldehyde and hydrogen peroxide. High resolution crystal structures are available for free MSOX and complexes of the enzyme with competitive inhibitors (, ). MSOX contains 1 mol of FAD, attached to the protein via a thioether linkage between the 8α-methyl group of the isoalloxazine ring and Cys315 (8α-S-cysteinyl-FAD) () (see for structure). The same covalent linkage is found for FAD in monoamine oxidase A and B, mammalian enzymes that exhibit 20% sequence identity with MSOX. In other enzymes, tyrosine or histidine may replace cysteine as the site of flavin attachment but the covalent linkage nearly always involves the 8α-methyl group of the flavin ().
Sarcosine dehydrogenase - Wikipedia
MT is considered as a possible marker of PCa(–). As certain studies have indicated,its levels are elevated in the blood serum of patients sufferingfrom PCa, independent of their state of health (,).Chip capillary electrophoresis (Experion) was used for thedetermination of MT levels. The assumed molecular weight of MTvaries from 6 to 15 kDa ();however, this depends on the type of isoform and the rate ofoxidation (,). From the Experion records, it isevident that PC-3 cells cultivated for 12 h synthesised MT withmolecular weights of 11, 15 and 19 kDa (see MT peaks, ). These results are also visible onvirtual output (). Theheight of these peaks increased depending on the applied sarcosineconcentration up to 1,000 μM. On the other hand, a distinctincrease in all three peaks was determined for the highest appliedconcentration of sarcosine (1,500 μM); however, this increase wasbelow the level of statistical significance. This trend is shown in. Furthermore, PC-3 cellsaffected by sarcosine were investigated electrochemically using theBrdicka reaction, which is a highly sensitive method for thedetermination of MT levels (,).As shown in , the MT levelwas reduced with the highest applied sarcosine concentration (1,500μM) in a time-dependent manner. This trend confirmed the resultsobtained by the chip capillary electrophoresis method. As regardsthe dependence of mentioned variables, we revealed a significantpositive correlation between sarcosine and MT (r=0.41 at P=0.03,). Moreover, no othersignificant dependencies were identified across variables,including markers of oxidative capacity.
Effects of substrate and potassium on the betaine-synthesizing enzyme glycine sarcosine dimethylglycine N-methyltransferase from a halophilic methanoarchaeon Methanohalophilus portucalensis.