Enzyme Activities in Human Liver Biopsies: Assay Methods and Activities of Some Lysosomal and Membrane-Bound Enzymes in Control Tissue and Serum

Abstract

1. Highly sensitive technique are described for the assay of plasma membrane (5'-nucleotidase, alkaline phosphatase), microsomal (neutral alpha-glucosidase, leucyl-2-naphthylamidase) and biliary canalicular (gamma-glutamyltransferase) enzymes and for nine acid hydrolases (acid phosphatase, phosphodiesterase, beta-glucosidase, alpha-glucosidase, alpha-galactosidase, beta-galactosidase, alpha-mannosidase, N-acetyl-beta-glucosaminidase, beta-glucuronidase) in human liver. 2. Optimum and specific assay systems have been developed which give linear kinetics for all enzymes. 3. The range of enzyme activities in samples of human liver, obtained by closed needle biopsy, and sera have been determined.

Glucagon-stimulable adenylyl cyclase in rat liver. The impact of streptozotocin-induced diabetes mellitus.

“…Since relative hyperinsulinism for a prolonged period of time is generally required for adequate suppression of the The levels of membrane-associated markers were determined in whole homogenates and plasma membrane preparations of livers of control rats, rats treated with a single dose of 150 mg/kg streptozotocin, and rats treated with 5 U insulin/d initiated 72 h after streptozotocin treatment. Levels and activities were assessed as described more fully in Methods by using the method of Brune et al (29) for DNA levels, a modification of the method of Seymour and Peters (32) for N-acetyl-,8-glucosaminidase activity, the method of Aronson and Touster (31) for glucose-6-phosphatase levels, and the method of Wharton and Tzagoloff (30) for cytochrome c oxidase activities. Each marker was measured in at least three preparations.…”

Pulmonary and Hepatic Activities of Membrane-Bound Enzymes in Man and Rat

“…Thus, the formation of adenosine from AMP is catalyzed not only by the specific 5'-nucleotidase, a substrate (j3-glycerophosphate) which 'diverts' the other phosphatases, but also by radioactive AMP added to the assay system (15). In tissues with high alkaline phosphatase activity, such as rat lung, this method of quanti fication of 5'-nucleotidase is not a very accurate one.…”

Intracellular Distribution of Lysosomal Sialidase Is Controlled by the Internalization Signal in Its Cytoplasmic Tail

“…Sialidase, N-acetyl-␤-hexosaminidase, ␤-galactosidase, and ␤-glucosidase activities were assayed in cellular homogenates using the corresponding 4-methylumbelliferyl (muf)-glycoside substrates as described (21)(22)(23)(24). Cathepsin A activity was determined with CBZ-Phe-Leu (28).…”