Glycine methyltransferase

Konishi, K., and Fujioka, M. (1987) Chemical modification of a functional arginine residue of rat liver glycine methyltransferase. Biochemistry 26, 8496-8502. 

Methyltransferases that utilize S-adenosyl-L-methionine as the methyl donor (and thus generating S-adenosyl-L-homocysteine) catalyze (a) A-methylation (e.g., norepinephrine methyltransferase, histamine methyltransferase, glycine methyltransferase, and DNA-(adenine-A ) methyltransferase), (b) O-methylation (e.g., acetylsero-tonin methyltransferase, catechol methyltransferase, and tRNA-(guanosine-0 ) methyltransferase), (c) S-methyl-ation (e.g., thiopurine methyltransferase and methionine S-methyltransferase), (d) C-methylation (eg., DNA-(cy-tosine-5) methyltransferase and indolepyruvate methyltransferase), and even (e) Co(II)-methylation during the course of the reaction catalyzed by methionine syn-thase. ... 

GLYCINE METHYLTRANSFERASE HISTAMINE N-METHYLTRANSFERASE HOMOCYSTEINE METHYLTRANSFERASE... 

The laboratory measurement of AdoMet and AdoHcy is not routinely performed, but plays an increasing role in studies of pathogenesis of elevated Hey as well as the differential diagnosis of hypermethioninaemia due to deficiency of MAT, glycine methyltransferase or AdoHcy hydrolase. 

H Ogawa, K Konishi, Y Takata, HNakashima, M Fujioka. Rat glycine methyltransferase. Complete amino acid sequence deduced from a cDNA clone and characterization of the genomic DNA. Eur J Biochem 168 141-151, 1987. 

Fig. 20.3 Pathway of methionine metabolism. The numbers represent the following enzymes or sequences (1) methionine adenosyltransferase (2) S-adenosylmethionine-dependent transmethylation reactions (3) glycine methyltransferase (4) S-adenosylhomocysteine hydrolase (5) betaine-homocysteine methyltransferase (6) 5-methyltetrahydrofolate homocysteine methyltransferase (7) serine hydroxymethyltransferase (8) 5,10-methylenetetrahydrofolate reductase (9) S-adenosylmethionine decarboxylase (10) spermidine and spermine synthases (11) methylthio-adenosine phosphorylase (12) conversion of methylthioribose to methionine (13) cystathionine P-synthase (14) cystathionine y-lyase (15) cysteine dioxygenase (16) cysteine suplhinate decarboxylase (17) hypotaurine NAD oxidoreductase (18) cysteine sulphintite a-oxoglutarate aminotransferase (19) sulfine oxidase. MeCbl = methylcobalamin PLP = pyridoxal phosphate...

Glycine A-methyltransferase is also reported to have an ordered binding mechanism with SAM binding first to the enzyme, there being no metal-ion dependency. Cooperative behavior is observed with SAM binding. The cooperative nature can be eliminated by the tryptic hydrolysis of the N-terminal eight amino acid residues. 

Fig. 2.2.1 Outline of homocysteine metabolism in man. BMT Betaine methyltransferase, cblC cobalamin defect type C, cblD cobalamin defect type D, GNMT def glycine N-methyltransferase deficiency, MAT methionine adenosyl transferase, MeCbl methylcobalamin, Met Synth methionine synthase, MTHFR methylenetetrahydrofolate reductase, SAH Hyd dc/S-adenosylhomocys-...

Yeo E, Wagner C (1994) Tissue binding of glycine N-methyltransferase, a major folate-binding protein of liver. Proc Natl Acad Sci U S A 91 210-214... 

Table 7.2.5 Pathological values for Cr and GA. AGAT L-Arginine glycine amidinotransferase, GAMT guanidinoacetate methyltransferase...

Glycine N-methyltransferase 591,593s Glycine reductase 824 Glycocalyx 6... 

Caffeic acid is metabolized by liver enzymes to give ferulic, vanillic acids and their glycine conjugates, which may be excreted into urine. In addition, dihydroferulic acid is produced by catechol o-methyltransferase in the liver. Because of the specificity of this enzyme, only ortho hydroxy-methoxy metabolites may be formed. These reactions may occur in rats as well in humans [15]. Fig. (2) shows the metabolic reactions of caffeic acid in body tissues. 

A third group of OMTs are the protein carboxyl MTs, whose molecular mass is approximately 27 kDa 43 These proteins are found in almost all organisms, and they serve to repair damaged proteins. In plants, they have been shown to be important during stress and in seed viability.14. Their sequences are related to the animal glycine N-methyltransferases (NMTs) and die RNA/DNA MTs. Furthermore, the plant protein carboxyl MTs share no similarity to the other plant MTs involved in specialized metabolism. The enzyme that methylates a carboxyl functionality of Mg-protoporphyrin IX to produce a methylester constitutes a fourth type of plant OMT. This chloroplastic protein, whose mature form has a molecular mass of 31 kDa, is related to MTs with similar functions from photosynthetic bacteria, but is not closely related to any other plant OMTs.6... 

At relatively high levels of intake, vitamin A induces synthesis of glycine Al-methyltransferase. This can lead to depletion of methyl groups and... 

Figure 14.4. Catabolism of choline. Choline dehydrogenase, EC 1.1.99.1 betaine aldehyde dehydrogenase, EC 1.2.1.8 and homocysteine methyltransferase, EC 2.1.1.5. Relative molecular masses (Mr) choline, 104.2 betaine, 117.2 dimethylglycine, 102.2 methylglycine, 88.2 and glycine, 74.2. THF, tetrahydrofolate.

Figure 14.5. Synthesis of creatine. Glycine gnanidotransferase (amidinotransferase), EC 2.1.4.1 gnanidinoacetate methyltransferase, EC 2.1.1.2 and creatine kinase, EC 2.7.3.2.

Rowling MJ, McMullen MH, and Schalinske KL (2002) Vitamin A and its derivatives induce hepatic glycine JV-methyltransferase and hypomethylation of DNA in rats. Journal of Nutrition 132,365-9. 

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