A novel calcium-independent enzyme capable of incorporating putrescine into proteins.
A Ca(++)-independent enzyme capable of incorporating [3H]-putrescine into proteins was detected in the rat intestine mucosa. The Ca(++)-independent incorporation of [3H]-putrescine into proteins was temperature-, pH-, time-, and dose-dependent. However, this enzyme was absent in the gastric mucosa. Similar to testicular Ca(++)-dependent transglutaminase, the optimal pH of intestinal Ca(++)-independent enzyme was 9.0. At 10(-5) M or less putrescine concentrations, the Ca(++)-independent enzyme in an intestinal cytosol preparation showed a greater activity than did the Ca(++)-dependent transglutaminase. However, at higher putrescine concentrations, the latter showed a greater activity than did the former. Both the intestinal Ca(++)-dependent and independent enzymes were inhibited by cystamine, thermal labile at 50 degrees C and precipitated by 30 to 50% saturation of ammonium sulfate. The fact that these two enzymes shared many similar characteristics, with the exceptions of Ca(++)-requirement, suggests that they may have similar active site and intrinsic molecular function(s).
Tsai
Y H
YH
Graduate Institute of Cell and Molecular Biology, Taipei Medical College, Taiwan, Republic of China.
Lai
W F
WF
Chen
S H
SH
Johnson
L R
LR
D000645:Ammonium Sulfate; D000818:Animals; D002118:Calcium / Q000502:physiology*; D003600:Cytosol / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004386:Duodenum; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability; D005590:Fractional Precipitation; D005753:Gastric Mucosa / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000201:enzymology*; D008297:Male; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011700:Putrescine / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013696:Temperature; D013997:Time Factors; D011503:Transglutaminases / Q000378:metabolism
D011506:Proteins; D011503:Transglutaminases; D000645:Ammonium Sulfate; D002118:Calcium; D011700:Putrescine