Electrostatic stabilization in sperm whale and harbor seal myoglobins

Journal Article · Wed Oct 01 00:00:00 EDT 1980 · Biophys. J.; (United States)

DOI:https://doi.org/10.1016/S0006-3495(80)84916-2· OSTI ID:7032943

Gurd, F R.N. ^[1]; Friend, S H; Rothgeb, T M; Gurd, R S; Scouloudi, H

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1. Indiana Univ., Bloomington

The compact, largely helical structure of sperm whale and harbor seal myoglobins undergoes an abrupt one-step transition between pH 4.5 and 3.5 as monitored by changes in either the heme Soret band absorbance or circular dichroism probes of secondary structure, for which a modified Tanford-Kirkwood theory provides identification of certain dominant electrostatic interactions responsible for the loss of stability. A similar treatment permits identification of the electrostatic interactions primarily responsible for a process in which the anchoring of the A helix to other parts of the molecule is weakened. This process is detected with both myoglobins, in a pH range approx. 1 unit higher than the onset of the overall unfolding process, through changes in the circular dichroic spectra near 295 nm which correspond to the L/sub a/O-O band of the only two tryptophan residues in these proteins, residues 7 and 14. In each case protonation of certain sites in neighboring parts of the molecule can be identified as producing destabilizing interactions with components of the A helix, particularly with lysine 16.

• OSTI ID: 7032943
• Journal Information: Biophys. J.; (United States), Journal Name: Biophys. J.; (United States) Vol. 32:1; ISSN BIOJA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTRA
CARBOXYLIC ACIDS
CONFIGURATION
DICHROISM
GLOBIN
HELICAL CONFIGURATION
HELICAL INSTABILITY
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INSTABILITY
INTERMEDIATE STRUCTURE
INTERMOLECULAR FORCES
MOLECULAR STRUCTURE
MYOGLOBIN
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PH VALUE
PIGMENTS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PORPHYRINS
PROTEINS
SPECTRA
STABILIZATION
STRUCTURAL CHEMICAL ANALYSIS