Chemical modification of cassava linamarase
2
Issued Date
2024
Copyright Date
1993
Resource Type
Language
eng
File Type
application/pdf
No. of Pages/File Size
x, 98 leaves : ill.
Access Rights
open access
Rights
ผลงานนี้เป็นลิขสิทธิ์ของมหาวิทยาลัยมหิดล ขอสงวนไว้สำหรับเพื่อการศึกษาเท่านั้น ต้องอ้างอิงแหล่งที่มา ห้ามดัดแปลงเนื้อหา และห้ามนำไปใช้เพื่อการค้า
Rights Holder(s)
Mahidol University
Bibliographic Citation
Thesis (M.Sc. (Biochemistry))--Mahidol University, 1993
Suggested Citation
Pantipa Subhasitanont Chemical modification of cassava linamarase. Thesis (M.Sc. (Biochemistry))--Mahidol University, 1993. Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/100902
Title
Chemical modification of cassava linamarase
Alternative Title(s)
การดัดแปลงทางเคมีของเอนไซม์ลิมานาเรสในมันสำปะหลัง
Author(s)
Advisor(s)
Abstract
Chemical modifications of linamarase from cassava petiole were carried out under mild conditions. Loss of β-glucosidase (linamarase) and β-fucosidase activities was observed when modifications were made on carboxyl, tryptophan, histidine, tyrosine and arginine residues. However, modification of Iysine only affected the B-glucosidase (linamarase) but not β-fucosidase activity. The loss of both activities due to the modifications of carboxyl, tryptophan and histidine residues was reduced in the presence of a competitive inhibitor, δ-gluconolactone. However, δ-gluconolactone has no effect on the loss of linamarase activity due to the modification of Iysine, arginine or tyrosine. In addition, δ-gluconolactone decreased the loss of β-fucosidase activity due to tyrosine modification. However, it showed no reduction on the loss of β-fucosidase activity after dialysis. These data suggested that carboxyl (aspartic and glutamic acids), tryptophan and histidine residues were located at the active site of cassava linamarase. By non-denaturing polyacrylamide gel electrophoresis, effects of the chemical modifications on the enzyme structure were studied. The modification of carboxyl groups gave a smear of slow moving bands suggesting that the surface negative charges were reduced by the modification. Modification of tryptophan did not change the ladder-like pattern of bands in the gel. However, the modifications of histidine, tyrosine, Iysine and arginine induced more net negative charges or structural changes to expose more negative charges on the enzyme and hence the enzyme bands that moved faster. The effects of chemical modifications on the molecular size of linamarase were investigated using a Superose 6 column and FPLC. After modification of carboxyl, tryptophan, histidine, tyrosine, Iysine or arginine residues, the molecular size of the enzyme remained in the same range as that of unmodified enzyme, MW = 440,000-2,000,000. However, after Iysine modification, the large molecular aggregates were not found, only the aggregate of 440,000 was present.
Description
Biochemistry (Mahidol University 1993)
Degree Name
Master of Science
Degree Level
Master's degree
Degree Department
Faculty of Science
Degree Discipline
Biochemistry
Degree Grantor(s)
Mahidol University