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Two distinct classes of rat intestinal mucosal enzymes incorporating putrescine into protein
Author(s) -
Tsai Yu-Hui,
Lai Wen-Fu Thomas,
Wu Yu-Wei,
Johnson Leonard R
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01062-x
Subject(s) - cadaverine , putrescine , spermidine , spermine , divalent , enzyme , chemistry , tissue transglutaminase , biochemistry , diamine oxidase , egta , microbiology and biotechnology , calcium , biology , organic chemistry
Tissue‐transglutaminase (t‐TGase) is a family of calcium‐dependent enzymes. A Ca 2+ ‐independent soluble enzyme, in addition to t‐TGase, capable of incorporating polyamines into proteins was demonstrated in rat intestinal mucosa. The Ca 2+ ‐independent enzyme was stimulated 2‐ to 5‐fold by Fe 2+ and Co 2+ ions but inhibited by Cu 2+ and Zn 2+ ions. The Ca 2+ ‐stimulated t‐TGase activity was inhibited by divalent ions in the following order: Zn 2+ , Fe 2+ >Co 2+ >Cu 2+ . The opposite effects of EGTA, Fe 2+ and Co 2+ on these two enzyme activities indicate that they are two distinct classes of enzymes. Competition studies demonstrated differential preferences of the two enzymes for substrates. The Ca 2+ ‐dependent enzyme preferred putrescine, monodansylcadaverine>cadaverine, spermidine, spermine>1,10‐diaminodecane>triethylbutylamine. On the other hand, the Ca 2+ ‐independent enzyme preferred putrescine>cadaverine>spermine, 1,10‐diaminodecane>spermidine>monodansylcadaverine>triethylbutylamine. Further studies with divalent ions excluded the possible association of this novel Ca 2+ ‐independent enzyme with diamine oxidase. Finally, the Ca 2+ ‐independent enzyme had a higher affinity for putrescine ( K m =0.02 mM) than did Ca 2+ ‐dependent t‐TGase (0.2 mM). As judged by gel filtration on HiPrep Sephacryl 200 column, the Ca 2+ ‐independent enzyme had a molecular weight of ∼48 kDa, the intestinal Ca 2+ ‐dependent t‐TGase was about 188 kDa while that of testicular t‐TGase was about 96 kDa. In conclusion, the Ca 2+ ‐independent enzyme is stimulated by cobalt or ferric ions, and selectively incorporates aliphatic diamines or polyamines with symmetric amino groups. The observed Ca 2+ ‐independent enzyme activity is not related to diamine oxidase or its products. With a 10 times greater affinity for putrescine, the calcium‐independent, 48‐kDa intestinal enzyme may mediate polyamine function better than calcium dependent, 188‐kDa intestinal tissue transglutaminase in the intestinal mucosa.