Cold denaturation and sup 2 H sub 2 O stabilization of a staphylococcal nuclease mutant

Journal Article · Sun Sep 01 00:00:00 EDT 1991 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.88.17.7715· OSTI ID:5602925

Antonino, L C; Nakano, Takayuki; Fink, A L ^[1]; Kautz, R A; Fox, R O ^[2]

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1. Univ. of California, Santa Cruz (United States)
2. Yale Univ., New Haven, CT (United States)

Cold denaturation is now recognized as a general property of proteins but has been observed only under destabilizing conditions, such as moderate denaturant concentration of low pH. By destabilizing the protein using site-directed mutagenesis, the authors have observed cold denaturation at pH 7.0 in the absence of denaturants in a mutant of staphylococcal nuclease, which the authors call NCA S28G for a hybrid protein between staphylococcal nuclease and concanavalin A in which there is the point mutation Ser-28{yields}Gly. The temperature of maximum stability (t{sub max}) as determined by circular dichroism (CD) was 18.1C, and the midpoints of the thermal unfolding transitions (t{sub m}) were 0.6C and 30.0C. These values may be compared with the t{sub m} of 52.5C for wild-type staphylococcal nuclease, for which no cold denaturation was observed under these conditions. When the stability of the mutant was examined in {sup 2}H{sub 2}O by NMR, CD, or fluorescence, a substantial increase in the amount of folded protein at the t{sub max} was noted as well as a decrease in t{sub max}, reflecting increased stability.

• OSTI ID: 5602925
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 88:17; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
NUCLEASES
PROTEIN DENATURATION
STAPHYLOCOCCUS
MUTANTS
GUANIDINES
HEAVY WATER
MAGNETIC CIRCULAR DICHROISM
NUCLEAR MAGNETIC RESONANCE
TEMPERATURE EFFECTS
BACTERIA
CARBONIC ACID DERIVATIVES
DICHROISM
ENZYMES
ESTERASES
HYDROGEN COMPOUNDS
HYDROLASES
MAGNETIC RESONANCE
MICROORGANISMS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHODIESTERASES
PROTEINS
RESONANCE
WATER
550201* - Biochemistry- Tracer Techniques