STUDY OF THE CHEMICAL CHARACTERISTICS THE ISOENZYME OF FAILLIA HYPERCHOLINESTERASEMIA

C5 cholinesterase isoenzyme (C5) is found in the serum of patients with familial hypercholinesterasemia. The C5 band on electrophoresis migrates nearer to the cathode than the C4 band which is the major one in normal subjects. I studied about the chemical characteristics of C5 . The C5 band was separated using 4-15% gradient polyacrylamide gel electrophoresis. The active band of ChE isoenzyme was stained by butyrylthiocholine used as a substrate. The frequency of C5 variant in normal population was 1.2 %. The molecular weight of C5 was about 340,000 which was determined by gel filtration chromatography using highperformance liquid chromatography. When the serum of C5 variant was treated with various kinds of lectins including Con A, RCA 60, LCA, WGA and E-PHA, C5 as well as C 4 reacted .with Con A and RCA 60. Con A affinity chromatography of the serum with C 5 revealed that both C4 and C5 were in the fraction eluted with 0.5 M α-methylman-noside. When treated with neuraminidase, all fractions of isoenzymes were retarded to the cathode. Treatment of C5 with trypsin and bromelin produced an active band with the mobility of C4 and a new band on the anodal side of C4. When treated with phospholipase C and phospholipase D, C5 disappeared and an active band of the mobility of C4 appeared. High-performance ion-exchange ch omatographyof the serum with C 5 revealed a little difference between C4 and C5 on isoelectric point. C5 was separated from other cholinesterase isoenzymes (C1〜C4) by fraction a tion using (NH_4)_2SO_4. When the solution containing C5 was treated with trypsin and phospholipase C, C5 band disappeared and C4 band appeared. Therefore, it was suggested that C5 isoenzyme of ChE is a glycoprotein, which is similar to C4 and may be a complex form conjugated with phospholipid.