TY - JOUR
T1 - Calcium inhibition of rat liver catechol-O-methyltransferase
AU - Weinshilboum, Richard M.
AU - Raymond, Frederick A.
N1 - Funding Information:
3,4-Dihydroxyhenzoic acid (DBA) as substrate. These studies were performed with an assay procedure for the measurement of COMT activity in which 3,4-dihydroxybenzoic acid (DBA) served as a substrate for the enzyme \[4\]. In the presence of COMT and radioactively labeled S-adenosyl-l-methionine, DBA was converted to radioactively labeled 4-hydroxy-3-methoxybenzoic acid (vanillic acid). The reaction was * Supported in part by NIH Grants NS 11014 and ttL 17487-1, and by a Faculty Development Award in Clinical Pharmacology sponsored by the Pharmaceutical Manufacturers Association Foundation. Inc. (R.M.W.~.
PY - 1976/3/1
Y1 - 1976/3/1
N2 - The activity of partially purified rat liver catechol-O-methyltransferase (COMT) was measured by an assay procedure in which 3,4-dihydroxybenzoic acid was used as a substrate for the enzyme. Optimal enzyme activity was present at a concentration of MgCl2 of 10-3 M. The effects on COMT activity of a series of alkaline earth compounds were determined in the presence of optimal concentrations of MgCl2. CaCl2 and Ca(NO3)2 at concentrations of 10-3 M reduced COMT activity by 63 and 59 per cent respectively. BaCl2 and Sr(NO3)2 (10-3 M) did not decrease enzyme activity, nor did additional MgCl2 to a final [Mg2+] of 2 × 10-3 M) did not decrease enzyme activity and 0·50 × 10-3 M CaCl2 in the presence of different concentrations of 3,4-dihydroxybenzoic acid, S-adenosyl-1-methionine and MgCl2 was determined. In each case Lineweaver-Burk plots of these data were compatible with noncompetitive or "mixed" inhibition.
AB - The activity of partially purified rat liver catechol-O-methyltransferase (COMT) was measured by an assay procedure in which 3,4-dihydroxybenzoic acid was used as a substrate for the enzyme. Optimal enzyme activity was present at a concentration of MgCl2 of 10-3 M. The effects on COMT activity of a series of alkaline earth compounds were determined in the presence of optimal concentrations of MgCl2. CaCl2 and Ca(NO3)2 at concentrations of 10-3 M reduced COMT activity by 63 and 59 per cent respectively. BaCl2 and Sr(NO3)2 (10-3 M) did not decrease enzyme activity, nor did additional MgCl2 to a final [Mg2+] of 2 × 10-3 M) did not decrease enzyme activity and 0·50 × 10-3 M CaCl2 in the presence of different concentrations of 3,4-dihydroxybenzoic acid, S-adenosyl-1-methionine and MgCl2 was determined. In each case Lineweaver-Burk plots of these data were compatible with noncompetitive or "mixed" inhibition.
UR - http://www.scopus.com/inward/record.url?scp=0017262792&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0017262792&partnerID=8YFLogxK
U2 - 10.1016/0006-2952(76)90390-7
DO - 10.1016/0006-2952(76)90390-7
M3 - Article
C2 - 8053
AN - SCOPUS:0017262792
SN - 0006-2952
VL - 25
SP - 573
EP - 579
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 5
ER -