Reduction of low-molecular-weight acid phosphatase activity in Alzheimer brains.
Recent studies in Alzheimer brains have shown aberrant protein phosphorylation, suggesting an alteration in protein kinases and/or phosphoprotein phosphatases. In the present study, the activity of acid phosphatase was investigated in samples prepared from postmortem normal human and Alzheimer brains. p-Nitrophenyl phosphate, a nonprotein phosphoester, was used as a substrate for acid phosphatase. The separation profile on Sephadex G-100 gel filtration chromatography revealed that two major forms of high-molecular-weight and low-molecular-weight acid phosphatase were present in the crude extracts of both rat and human brains. Another class of zinc ion (Zn2+)-dependent acid p-nitrophenyl phosphatase was also detected in rat and human brains. In Alzheimer brains, the low-molecular-weight acid phosphatase activity was significantly decreased compared to that in control brains; however, the high-molecular-weight and Zn(2+)-dependent acid phosphatase activity in control and Alzheimer brains was not different. These results suggest that reduced activity of the low-molecular-weight acid phosphatase, which possesses phosphotyrosine protein phosphatase activity, might be linked to aberrant protein tyrosine phosphorylation found in Alzheimer brains.
Shimohama
S
S
Department of Neurology, Faculty of Medicine, Kyoto University, Japan.
Fujimoto
S
S
Taniguchi
T
T
Kameyama
M
M
Kimura
J
J
D000135:Acid Phosphatase / Q000302:isolation & purification / Q000378:metabolism*; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000201:enzymology* / Q000473:pathology; D002850:Chromatography, Gel; D004795:Enzyme Stability; D006624:Hippocampus / Q000201:enzymology; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008875:Middle Aged; D008970:Molecular Weight; D011180:Postmortem Changes; D051381:Rats; D012016:Reference Values; D013702:Temporal Lobe / Q000201:enzymology
D007527:Isoenzymes; D000135:Acid Phosphatase