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Inhibition of the Vacuolar-like ATPase from Halobacterium saccharovorum by Thiol Reagents: Evidence for Different Functional ThiolsN-Ethylmaleimide (NEM) inhibited the vacuolar-like ATPase from Halobacterium saccharovorum (K(sub i) approximately 1 mM) by modifying one or more of the thiols located on the largest of the subunit. ATP protected against inhibition and coincidentally prevented NEM binding which suggested that NEM acts at or near the catalytic site. p-Chloromercuriphenylsulfonate (PCMS) also inhibited this ATPase (K(sub i) approximately 90 microM). ATP did not protect against PCMS inhibition. Dithiothreitol (DTT) partially reversed PCMS inhibition and restored approximately half of the initial activity of 90% inhibited enzyme. DTT did not restore activity of the NEM-inhibited enzyme or the PCMS-inhibited enzyme when it was subsequently incubated with NEM. The failure of ATP to protect against PCMS inhibition and the inability of DTT to restore activity of enzyme incubated in the presence of PCMS and NEM suggests these reagents react with different thiols and that the PCMS-sensitive thiol may have a structural role.
Document ID
Document Type
Conference Paper
Hochstein, L. I.
(NASA Ames Research Center Moffett Field, CA United States)
Stanlotter, H.
(Wien Univ. Austria)
Emrich, E.
(Search for Extraterrestrial Intelligence Inst. Mountain View, CA United States)
Morrison, David
Date Acquired
August 20, 2013
Publication Date
January 1, 1994
Subject Category
Life Sciences (General)
Meeting Information
94th General Meeting of the American Society for Microbiology(Las Vegas, NV)
Funding Number(s)
PROJECT: RTOP 185-52-32
Distribution Limits
Work of the US Gov. Public Use Permitted.

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