The structure and properties of the isozymes of cassava linamarase
1
Issued Date
1991
Copyright Date
1991
Resource Type
Language
eng
File Type
application/pdf
No. of Pages/File Size
xi, 122 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, 1991
Suggested Citation
Kannika Sermsuvitayawong The structure and properties of the isozymes of cassava linamarase. Thesis (M.Sc. (Biochemistry))--Mahidol University, 1991. Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/103293
Title
The structure and properties of the isozymes of cassava linamarase
Alternative Title(s)
การศึกษาโครงสร้างและคุณสมบัติของไอโซโซม์ของเอ็นไซม์ลินามาเรสจากมันสำปะหลัง
Author(s)
Advisor(s)
Abstract
Purified linamarase (EC.3.2.1.21) from cassava petiole, stem and root cortex were shown to have native M(,r) of 600,000 - 2,000,000 on Sepharose 4B chromatiography. Structure was analysed by electrophoresis under both denaturing and non-denaturing conditions. Linamarase from all three sources showed subunit M(,r) of about 63,000 after denaturation by 1% SDS and heat. Analysis of the enzme in acid-urea gels and triton-acid-urea gels showed that linamarase gave the same single band for enzyme from three sources, suggesting linamarase consisted of a single peptide chain. On isoelectric focusing in agarose gels without denaturing agent, linamarase from petiole and stem gave one major (pI 4.6) band, while linamarase from root cortex gave a double band (pI 4.5-4.6). Under non-denaturing conditions, the purified linamarase appeared as a ladder pattern with more than 6 active bands in alkalind PAGE but failed to show a ladder pattern, appearing as a single broad band in cellulose acetate electro phoresis. Since the latter has no sieving effect, these results suggested that linamarase is present as aggregates with various MW sizes. The presence of a ladder pattern in fresh extract was confirmed and suggested the possibility that such aggregates existed in vivo, with the prominents forms consisting of even subunit numbers, namely 4, 6, 8, 10, and larger multiples. On 2 dimensional non-denaturing PAGE, stem linamarase showed little interconcersion of aggregated forms. Data obtained from the partial separation of high MW forms and low MW forms on Sepharose 4B chromatography and demonstration of effect of urea on linamarase aggregates suggest that existence of linamarase aggregates of appropriate size are needed for improved specificity towards linamarin. Re-evaluation of the different forms eluted at different pH (pH 4.3. 3.3 and 2.9 on chromatofocusing showed no diffisoelectric focusing, suggesting that all three forms may have the same pI. In addition, the kpattern obtained on non-denaturing PAGE suggested that the different chromatofocusing forms may be due to the differences in aggregate size. Amino acid analysis showed no difference between linamarase from the three tissues. The composition showed that the content of acidic amino, acids (Glx + Asx) was double the content of basic amino acids (Lys + Arg + His), consistent with the enzymes low pI. Furthermors, the content of hydrophobic amino scids (Ala, Val, Leu, Ile, Pro, Phe, Tyr) was high and approachen 50% of the total amino acids.
Description
Biochemistry (Mahidol University 1991)
Degree Name
Master of Science
Degree Level
Master's degree
Degree Department
Faculty of Science
Degree Discipline
Biochemistry
Degree Grantor(s)
Mahidol University