Asparagine as a nitrogen source for improving the secretion of mouse ?-amylase inSaccharomyces cerevisiae protease A-deficient strains
✍ Scribed by Chen, Dz-Chi; Wang, Bi-Dar; Chou, Pei-Yin; Kuo, Tsong-Teh
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 217 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0749-503X
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✦ Synopsis
A modi®ed chemically de®ned medium was achieved by using asparagine as a nitrogen source to increase the production of secreted mouse a-amylase in several Saccharomyces cerevisiae protease A-de®cient (pep4) strains. The speci®c productivity (quantity) and the 53 kDa non-glycosylated active form (quality) of mouse salivary a-amylase in liquid medium containing asparagine was remarkably improved compared to media containing other nitrogen sources, including ammonium sulphate, glutamic acid, arginine, casamino acids, yeast extract and peptone. Similar improvement was also observed on starch solid agar regarding the clarity and size of the halo zone formed by aamylase activity. Compared with ammonium sulphate, advantages of using asparagine as the nitrogen source in liquid or solid medium included increasing the cell mass of test strains, recovering the viability of protease-de®cient strains to levels similar to the wild-type strain, and increasing the copy number of the mouse a-amylase expression vector in test strains. In turn, these advantages apparently contributed to the increase of secretion of mouse aamylase in several test strains and especially in the protease A-de®cient strains. In addition to demonstrating the use of modi®ed chemically de®ned medium to improve the quality and quantity of secreted mouse a-amylase, this study also provides a new strategy to improve the secretion of heterologous proteins in protease A de®cient strains.