Proton‐Magnetic‐Resonance Spectroscopic Study of the Histidine Residues of Bovine α‐Lactalbumin

J. Howard Bradbury, Raymond S. Norton

Research output: Contribution to journalArticleResearchpeer-review

25 Citations (Scopus)

Abstract

A study of the three histidine residues of bovine α‐lactalbumin has been made using proton magnetic resonance (PMR) spectroscopy in order to obtain information of their environments in the protein and thereby to test in part the previously proposed structure. PMR titration curves are obtained for the H‐4 resonances using difference spectroscopy and for the H‐2 resonances and the 1H–2H exchange rates of the H‐2 protons have been measured. The assignment of resonances to particular histidine residues is achieved by utilising their selective reaction with iodoacetate in conjunction with a PMR study of the carboxymethylation of α‐N‐acetyl‐l‐histidine. The H‐2 and H‐4 resonances labelled 1, 2and 3 starting from the downfield end of the spectrum are assigned to histidine residues 107, 68 and 32 respectively. Their apparent pK values at low ionic strength and 20°C are 5.78, 6.49 and 6.51 respectively. The experimental results on two histidine residues are consistent with the predictions of the proposed structure, which indicate that histidine‐68 is an external residue and histidine‐32 is partially buried and in the vicinity of aromatic residues. The experimental data on histidine 107 can also be rationalised with less certainty in terms of the proposed structure, which indicates a partially buried residue that may be involved in hydrogen bonding.

Original languageEnglish
Pages (from-to)387-396
Number of pages10
JournalEuropean Journal of Biochemistry
Volume53
Issue number2
DOIs
Publication statusPublished - 1975
Externally publishedYes

Cite this

@article{2ffd2c5069fa40528fe45a300914b292,
title = "Proton‐Magnetic‐Resonance Spectroscopic Study of the Histidine Residues of Bovine α‐Lactalbumin",
abstract = "A study of the three histidine residues of bovine α‐lactalbumin has been made using proton magnetic resonance (PMR) spectroscopy in order to obtain information of their environments in the protein and thereby to test in part the previously proposed structure. PMR titration curves are obtained for the H‐4 resonances using difference spectroscopy and for the H‐2 resonances and the 1H–2H exchange rates of the H‐2 protons have been measured. The assignment of resonances to particular histidine residues is achieved by utilising their selective reaction with iodoacetate in conjunction with a PMR study of the carboxymethylation of α‐N‐acetyl‐l‐histidine. The H‐2 and H‐4 resonances labelled 1, 2and 3 starting from the downfield end of the spectrum are assigned to histidine residues 107, 68 and 32 respectively. Their apparent pK values at low ionic strength and 20°C are 5.78, 6.49 and 6.51 respectively. The experimental results on two histidine residues are consistent with the predictions of the proposed structure, which indicate that histidine‐68 is an external residue and histidine‐32 is partially buried and in the vicinity of aromatic residues. The experimental data on histidine 107 can also be rationalised with less certainty in terms of the proposed structure, which indicates a partially buried residue that may be involved in hydrogen bonding.",
author = "Bradbury, {J. Howard} and Norton, {Raymond S.}",
year = "1975",
doi = "10.1111/j.1432-1033.1975.tb04078.x",
language = "English",
volume = "53",
pages = "387--396",
journal = "European Journal of Biochemistry",
issn = "0014-2956",
publisher = "Wiley-Blackwell",
number = "2",

}

Proton‐Magnetic‐Resonance Spectroscopic Study of the Histidine Residues of Bovine α‐Lactalbumin. / Bradbury, J. Howard; Norton, Raymond S.

In: European Journal of Biochemistry, Vol. 53, No. 2, 1975, p. 387-396.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Proton‐Magnetic‐Resonance Spectroscopic Study of the Histidine Residues of Bovine α‐Lactalbumin

AU - Bradbury, J. Howard

AU - Norton, Raymond S.

PY - 1975

Y1 - 1975

N2 - A study of the three histidine residues of bovine α‐lactalbumin has been made using proton magnetic resonance (PMR) spectroscopy in order to obtain information of their environments in the protein and thereby to test in part the previously proposed structure. PMR titration curves are obtained for the H‐4 resonances using difference spectroscopy and for the H‐2 resonances and the 1H–2H exchange rates of the H‐2 protons have been measured. The assignment of resonances to particular histidine residues is achieved by utilising their selective reaction with iodoacetate in conjunction with a PMR study of the carboxymethylation of α‐N‐acetyl‐l‐histidine. The H‐2 and H‐4 resonances labelled 1, 2and 3 starting from the downfield end of the spectrum are assigned to histidine residues 107, 68 and 32 respectively. Their apparent pK values at low ionic strength and 20°C are 5.78, 6.49 and 6.51 respectively. The experimental results on two histidine residues are consistent with the predictions of the proposed structure, which indicate that histidine‐68 is an external residue and histidine‐32 is partially buried and in the vicinity of aromatic residues. The experimental data on histidine 107 can also be rationalised with less certainty in terms of the proposed structure, which indicates a partially buried residue that may be involved in hydrogen bonding.

AB - A study of the three histidine residues of bovine α‐lactalbumin has been made using proton magnetic resonance (PMR) spectroscopy in order to obtain information of their environments in the protein and thereby to test in part the previously proposed structure. PMR titration curves are obtained for the H‐4 resonances using difference spectroscopy and for the H‐2 resonances and the 1H–2H exchange rates of the H‐2 protons have been measured. The assignment of resonances to particular histidine residues is achieved by utilising their selective reaction with iodoacetate in conjunction with a PMR study of the carboxymethylation of α‐N‐acetyl‐l‐histidine. The H‐2 and H‐4 resonances labelled 1, 2and 3 starting from the downfield end of the spectrum are assigned to histidine residues 107, 68 and 32 respectively. Their apparent pK values at low ionic strength and 20°C are 5.78, 6.49 and 6.51 respectively. The experimental results on two histidine residues are consistent with the predictions of the proposed structure, which indicate that histidine‐68 is an external residue and histidine‐32 is partially buried and in the vicinity of aromatic residues. The experimental data on histidine 107 can also be rationalised with less certainty in terms of the proposed structure, which indicates a partially buried residue that may be involved in hydrogen bonding.

UR - http://www.scopus.com/inward/record.url?scp=0016702734&partnerID=8YFLogxK

U2 - 10.1111/j.1432-1033.1975.tb04078.x

DO - 10.1111/j.1432-1033.1975.tb04078.x

M3 - Article

VL - 53

SP - 387

EP - 396

JO - European Journal of Biochemistry

JF - European Journal of Biochemistry

SN - 0014-2956

IS - 2

ER -