The cytochemical assay of NAD+ kinase activity in the follicular cells of guinea-pig thyroid gland |
| |
Authors: | H. Perrild J. Frost W. R. Robertson |
| |
Affiliation: | (1) Department of Internal Medicine and Endocrinology F, Herlev Sygehus, 2730 Herlev, Denmark;(2) Department of Chemical Pathology, University of Manchester, Clinical Sciences Building, Hope Hospital, Eccles Old Road, M6 8HD Salford, UK |
| |
Abstract: | Summary A quantitative cytochemical assay for NAD+ kinase-like activity in the guinea-pig thyroid gland is described. The NADP+ produced by the activity of the kinase was used to drive the NADP+-dependent enzyme glucose-6-phosphate dehydrogenase which is endogenous to the tissue. The activity of glucose-6-phosphate dehydrogenase is greatly in excess of that of the kinase and was unaffected by the constituents of the kinase incubation medium (ATP, Mg2+ and NAD+) either alone or in combination. Kinase activity was dependent both on ATP and Mg2+, with maximal activity seen when the Mg-ATP ratio was between 1:1 and 4:1. Free ATP inhibited the activity of the enzyme. Enzyme activity was exhibited over a broad pH range (7–9) with a peak at pH 8.2. The sulphhydryl-blocking agents,p-chloromercuribenzoate, iodoacetate and iodoacetamide (at 1 mM), completely abolished kinase activity but were without effect on glucose-6-phosphate dehydrogenase activity.N-ethylmaleimide and citrate (both at 1 mM) had no effect on either kinase or glucose-6-phosphate dehydrogenase activities. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|