Evidence for conversion of human salivary alpha-amylase family A to family B by an enzyme action.
SDS-PAGE showed that human salivary alpha-amylase family A (HSA-A) was converted to family B (HSA-B) in human saliva. This conversion did not occur in the supernatant of saliva which had been centrifuged at 105,000 x g for 60 min. An enzyme which catalyzed the conversion existed in the insoluble fraction of human saliva. The enzyme was solubilized with nonionic or zwitterionic detergents, and showed the maximum activity around pH 6. It was stable between pH 4 and 10, and at a temperature lower than 40 degrees C. The enzyme reduced the molecular weight of HSA-A (62,000) to the same molecular weight (58,000) as that of HSA-B without forming any intermediate. It also changed the PAGE pattern of multiple forms of HSA-A to the same pattern as that of HSA-B. It was not inhibited by protease inhibitors, and it did not destroy the reactivity of HSA-A with anti-human salivary alpha-amylase antiserum. The enzyme diminished the reactivity of HSA-A with concanavalin A. These results indicate that HSA-A was converted to HSA-B through the release of sugar chains by the action of the enzyme in the insoluble fraction of human saliva.
Ito
K
K
Department of Biology, Faculty of Science, Osaka City University.
Li
L F
LF
Nishiwaki
M
M
Okada
Y
Y
Minamiura
N
N
D002384:Catalysis; D003208:Concanavalin A / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007106:Immune Sera / Q000737:chemistry; D007527:Isoenzymes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D012463:Saliva / Q000201:enzymology*; D012471:Salivary Proteins and Peptides / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D012995:Solubility; D000516:alpha-Amylases / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
D007106:Immune Sera; D007527:Isoenzymes; D012471:Salivary Proteins and Peptides; D003208:Concanavalin A; D000516:alpha-Amylases