Side-chain dynamics of a detergent-solubilized membrane protein: Measurement of tryptophan and glutamine hydrogen-exchange rates in M13 coat protein by sup 1 H NMR spectroscopy

Journal Article · Tue Aug 08 00:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00442a029· OSTI ID:5299218

O'Neil, J D.J.; Sykes, B D ^[1]

---

1. Univ. of Alberta, Edmonton (Canada)

M13 coat protein is a small (50 amino acids) lipid-soluble protein that becomes an integral membrane protein during the infection stage of the life cycle of the M13 phage and is therefore used as a model membrane protein. To study side-chain dynamics in the protein, the authors have measured individual hydrogen-exchange rates for a primary amide in the side chain of glutamine-15 and for the indole amine of tryptophan-26. The protein was solubilized with the use of perdeuteriated sodium dodecyl sulfate (SDS), and hydrogen-exchange rates were measured by using {sup 1}H nuclear magnetic resonance spectroscopy. The glutamine-15 syn proton exchanged at a rate identical with that in glutamine model peptides except that the pH corresponding to minimum exchange was elevated by about 1.5 pH units. The tryptophan-26 indole amine proton exchange was biphasic, suggesting that two populations of tryptophan-26 exist. It is suggested that the two populations may reflect protein dimerization or aggregation in the SDS micelles. The pH values of minimum exchange for tryptophan-26 in both environments were also elevated by 1.3-1.9 pH units. This phenomenon is reproduced when small tryptophan- and glutamine-containing hydrophobic peptides are dissolved in the presence of SDS micelles. The electrostatic nature of this phenomenon is proven by showing that the minimum pH for exchange can be reduced by dissolving the hydrophobic peptides in the positively charged detergent micelle dodecyltrimethylammonium bromide.

• OSTI ID: 5299218
• Journal Information: Biochemistry; (USA), Vol. 28:16; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
MEMBRANE PROTEINS
NUCLEAR MAGNETIC RESONANCE
MEMBRANES
PROTEINS
BIOCHEMICAL REACTION KINETICS
GLUTAMINE
HEAVY WATER
PH VALUE
PROTONS
TRYPTOPHAN
AMIDES
AMINO ACIDS
AROMATICS
AZAARENES
AZOLES
BARYONS
CARBOXYLIC ACIDS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INDOLES
KINETICS
MAGNETIC RESONANCE
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PYRROLES
REACTION KINETICS
RESONANCE
WATER
550601* - Medicine- Unsealed Radionuclides in Diagnostics