sup 1 H and sup 15 N NMR resonance assignments and preliminary structural characterization of Escherichia coli apocytochrome b sub 562

Journal Article · Tue Aug 06 00:00:00 EDT 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00245a007· OSTI ID:5700744

Feng, Yiqing; Sligar, S G ^[1]; Wand, A J ^[2]

---

1. Univ. of Illinois, Urbana (United States)
2. Univ. of Illinois, Urbana (United States) Fox Chase Cancer Center, Philadelphia, PA (United States)

The {sup 1}H and {sup 15}N resonances of uniformly enriched apocytochrome b{sub 562} (106 residues) have been assigned. The assignment work began with the identification of the majority of H{sup N}-H{sup {alpha}}-H{sup {beta}} subspin systems in two-dimensional DQF-COSY and TOCSY spectra of unlabeled protein in D{sub 2}O and in 95% H{sub 2}O/5% D{sub 2}O buffer. Intraresidue and interresidue NOE connectivities were then searched for in two-dimensional homonuclear NOESY spectra recorded on unlabeled protein and in the three-dimensional NOESY-HMQC spectrum recorded on uniformly {sup 15}N-enriched protein. Those data, combined with the main-chain-directed assignment strategy (MCD), led to the assignment of the main-chain and many side-chain resonances of 103 of the 106 residues. Qualitatively, the helical conformation is found to be the dominant secondary structure in apocytochrome b{sub 562} as it is holocytochrome b{sub 562}. The helical segments in apocytochrome b{sub 562} overlap extensively with the helical regions defined in the crystal structure of ferricytochrome b{sub 562}. In addition, a number of tertiary NOEs have been identified which indicate that the global fold of the apoprotein at least partially resembles the four-helix bundle of the holoprotein. The results presented here, together with the evidence obtained with other methods support the notion that the interior of the protein is fluid and may correspond to a molten globule state.

• OSTI ID: 5700744
• Journal Information: Biochemistry; (United States), Vol. 30:31; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CYTOCHROMES
NUCLEAR MAGNETIC RESONANCE
CHEMICAL SHIFT
ESCHERICHIA COLI
HEAVY WATER
NITROGEN 15
OVERHAUSER EFFECT
PROTONS
BACTERIA
BARYONS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HYDROGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MICROORGANISMS
NITROGEN ISOTOPES
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PIGMENTS
PROTEINS
RESONANCE
STABLE ISOTOPES
WATER
550601* - Medicine- Unsealed Radionuclides in Diagnostics