title: Structure-function investigations of the membrane (Na+ + Mg2+)-ATPase from Acholeplasma laidlawii B: studies of reactive amino acid residues using group-specific reagents.
abstract: The purified, lipid-reconstituted (Na+ + Mg2+)-ATPase from Acholeplasma laidlawii B was treated with a variety of reagents which specifically modify various amino acid residues on the enzyme. In all cases reaction of this enzyme with any of the reagents tested results in at least a partial inactivation of its activity. The modification of one reactive lysine by dinitrofluorobenzene, of one reactive arginine by phenylglyoxal, or of two tyrosine residues by 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole or fluorosulfonylbenzoyl adenosine results in a complete inactivation of the enzyme. Partial inactivation of enzymatic activity with N-ethylmaleimide, p-chloromercuribenzene sulfonic acid, dicyclohexylcarbodiimide, and Woodward's reagent K suggests an indirect involvement of sulfhydryl and carboxylic acid groups in the maintenance of enzymatic activity, although inhibition by these reagents may also be the result of nonspecific effects such as subunit crosslinking. These studies also show that all of the subunits of the ATPase can be labeled by aqueous-phase reagents directed at amino groups and phenolic groups, and provide evidence for a specific affinity labeling of the alpha subunit of the enzyme by a nucleotide analog directed at phenolic and/or sulfhydryl groups.
mesh_terms: D009327:4-Chloro-7-nitrobenzofurazan / Q000494:pharmacology; D000128:Acholeplasma laidlawii / Q000201:enzymology*; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000251:Adenosine Triphosphatases; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000596:Amino Acids / Q000032:analysis*; D017301:Ca(2+) Mg(2+)-ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D004139:Dinitrofluorobenzene / Q000494:pharmacology; D006146:Guanidines / Q000032:analysis; D007202:Indicators and Reagents; D007700:Kinetics; D010636:Phenols / Q000032:analysis; D010658:Phenylglyoxal / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000032:analysis
chemical_list: D000596:Amino Acids; D006146:Guanidines; D007202:Indicators and Reagents; D010636:Phenols; D013438:Sulfhydryl Compounds; C010959:5'-(4-fluorosulfonylbenzoyl)adenosine; D000255:Adenosine Triphosphate; D004139:Dinitrofluorobenzene; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; C035123:magnesium sodium ATPase; D009327:4-Chloro-7-nitrobenzofurazan; D000241:Adenosine; D010658:Phenylglyoxal