Hostname: page-component-586b7cd67f-tf8b9 Total loading time: 0 Render date: 2024-11-26T06:29:03.519Z Has data issue: false hasContentIssue false
  • English
  • Français

Factors affecting the thermostability of β-galactosidase (Streptococcus salivarius subsp. thermophilus) in milk: a quantitative study

Published online by Cambridge University Press:  01 June 2009

Byeong-Seon Chang  and
Raymond R. Mahoney
Byeong-Seon Chang
Affiliation:
Department of Food Science and Nutrition, Massachusetts Agricultural Experiment Station, University of Massachusetts, Amherst, MA 01003, USA
Raymond R. Mahoney
Affiliation:
Department of Food Science and Nutrition, Massachusetts Agricultural Experiment Station, University of Massachusetts, Amherst, MA 01003, USA
Get access Rights & Permissions [Opens in a new window]

Summary

Enhanced stability of β-galactosidase (Streptococcus salivarius subsp. thermophilus) in milk is due to several milk components acting in concert. Milk salts stabilized the enzyme 3-fold compared to phosphate buffer. K+ was a better stabilizer than Na+. Omission of divalent cations, especially Mg2+, caused a marked drop in stability. Lactose stabilized enzyme stored in the frozen state but destabilized enzyme stored unfrozen. Caseinate stabilized the enzyme 8-fold in phosphate buffer but it stabilized 144-fold in the presence of lactose. In the presence of milk proteins, lactose was 25 times as effective as galactose and 100 times as effective as glucose at promoting stability; sucrose slightly destabilized the enzyme. Stability rose with increasing lactose concentration but declined with increasing enzyme concentration. In milk, soluble casein was the primary stabilizer; whey proteins and peptides had much less effect. Micellar casein had no effect on stability.

Type
Original articles
Information
Journal of Dairy Research , Volume 56 , Issue 5 , November 1989 , pp. 785 - 792
Copyright
Copyright © Proprietors of Journal of Dairy Research 1989

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Arakawa, T. & Timasheff, S. N. 1982 Stabilization of protein structure by sugars. Biochemistry 21 6536–6544CrossRefGoogle ScholarPubMed
Back, J. F., Oakenfull, D. & Smith, M. B. 1979 Increased thermal stability of proteins in the presence of sugars and polyols. Biochemistry 18 5191–5196CrossRefGoogle ScholarPubMed
Chang, B-S. & Mahoney, R. R. 1989 Purification and thermostability of β-galactosidase (lactase) from an autolytic strain of Streptococcus salivarius subsp. thermophilus. Journal of Dairy Research 56 117–127Google Scholar
Chothia, C. & Janin, J. 1975 Principles of protein-protein recognition. Nature 256 705–708CrossRefGoogle ScholarPubMed
Citri, N. 1973 Conformational adaptability in enzymes. Advances in Enzymology 37 397–648Google Scholar
Green, M. L. & Marshall, R. J. 1977 The acceleration by cationic materials of the coagulation of casein micelles by rennet. Journal of Dairy Research 44 521–531Google Scholar
Greenberg, N. A. & Mahoney, R. R. 1982 Production and characterization of β-galactosidase from Streptococcus thermophilus. Journal of Food Science 47 1824–1828, 1835Google Scholar
Greenberg, N. A., Wilder, T. & Mahoney, R. R. 1985 Studies on the thermostability of lactase (Streptococcus thermophilus) in milk and sweet whey. Journal of Dairy Research 52 439–449CrossRefGoogle Scholar
Jacober-Pivarnik, L. F. & Rand, A. G. 1984 Use of a milk assay to evaluate the effects of potassium on commercial yeast lactases. Journal of Food Science 49 435–438, 445CrossRefGoogle Scholar
Jenness, R. & Koops, J. 1962 Preparation and properties of a salt solution which simulates milk ultrafiltrate. Netherlands Milk and Dairy Journal 16 153–164Google Scholar
Lowry, O. H., Rosebrough, N. J., Farr, A. L. & Randall, R. J. 1951 Protein measurement with the Folin phenol reagent. Journal of Biological Chemistry 193 265–275Google Scholar
Mahoney, R. R. & Wilder, T. 1988 Thermostability of yeast lactase (Kluyveromyces marxianus) in milk. Journal of Dairy Research 55 423–433CrossRefGoogle Scholar
Ramana Rao, M. V. & Dutta, S. M. 1981 Purification and properties of β-galactosidase from Streptococcus thermophilus. Journal of Food Science 46 1419–1423Google Scholar
Schmid, R. D. 1979 Stabilized soluble enzymes. In Immobilized Enzymes II pp. 41–118 (Eds Ghose, T. K., Fiechter, A. and Blakebrough, N.) New York: Springer-Verlag (Advances in Biochemical Engineering 12)Google Scholar
Silverstein, R. & Grisolia, S. 1972 Inactivation of enzymes induced by substrate: a model and some considerations. Physiological Chemistry and Physics 4 37–40Google Scholar
Smart, J. B., Crow, V. L. & Thomas, T. D. 1985 Lactose hydrolysis in milk and whey using β-galactosidase from Streptococcus thermophilus. New Zealand Journal of Dairy Science and Technology 20 43–56Google Scholar
Smart, J. B. & Richardson, B. 1987 Molecular properties and sensitivity to cations of β-galactosidase from Streptococcus thermophilus with four enzyme substrates. Applied Microbiology and Biotechnology 26 177–185CrossRefGoogle Scholar
Somkuti, G. A. & Steinberg, D. H. 1979 β-Galactoside galactohydrolase of Streptococcus thermophilus: induction, purification, and properties. Journal of Applied Biochemistry 1 357–368Google Scholar
Von Hippel, P. H. & Schleich, T. 1969 The effects of neutral salts on the structure and conformational stability of macromolecules in solution. In Structure and Stability of Biological Macromolecules pp. 417–574 (Eds Timasheff, S. N. and Fasman, G. D.) New York: Marcel DekkerGoogle Scholar