PDBsum entry 1vwt

Oxygen transport

PDB id: 1vwt

Contents

Protein chains

141 a.a. *

146 a.a. *

Ligands

HEM ×4

SO4 ×2

Waters ×243

* Residue conservation analysis

PDB id:

1vwt

Name:

Oxygen transport

Title:

T state human hemoglobin [alpha v96w], alpha aquomet, beta deoxy

Structure:

Hemoglobin. Chain: a, c. Synonym: r hb (alpha 96 val -> trp). Engineered: yes. Mutation: yes. Other_details: alpha aquomet, beta deoxy. Hemoglobin. Chain: b, d. Synonym: r hb (alpha 96 val -> trp).

Source:

Homo sapiens. Human. Organism_taxid: 9606. Tissue: blood. Cell: erythrocyte. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Tetramer (from PQS)

Resolution:

1.90Å R-factor: 0.169

Authors:

Y.A.Puius,M.Zou,N.T.Ho,C.Ho,S.C.Almo

Key ref:

Y.A.Puius et al. (1998). Novel water-mediated hydrogen bonds as the structural basis for the low oxygen affinity of the blood substitute candidate rHb(alpha 96Val-->Trp). Biochemistry, 37, 9258-9265. PubMed id: 9649306 DOI: 10.1021/bi9727287

Date:

20-Mar-97 Release date: 25-Mar-98

Protein chains

P69905  (HBA_HUMAN) -  Hemoglobin subunit alpha from Homo sapiens

Seq: 142 a.a.

Struc: 141 a.a.*

Protein chains

P68871  (HBB_HUMAN) -  Hemoglobin subunit beta from Homo sapiens

Seq: 147 a.a.

Struc: 146 a.a.

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: Chains A, B, C, D: E.C.?

DOI no: 10.1021/bi9727287

Biochemistry 37:9258-9265 (1998)

PubMed id: 9649306

Novel water-mediated hydrogen bonds as the structural basis for the low oxygen affinity of the blood substitute candidate rHb(alpha 96Val-->Trp).

Y.A.Puius, M.Zou, N.T.Ho, C.Ho, S.C.Almo.

ABSTRACT

One of the most promising approaches for the development of a synthetic blood substitute has been the engineering of novel mutants of human hemoglobin (Hb) A which maintain cooperativity, but possess lowered oxygen affinity. We describe here two crystal structures of one such potential blood substitute, recombinant (r) Hb(alpha 96Val-->Trp), refined to 1.9 A resolution in an alpha-aquomet, beta-deoxy T-state, and to 2.5 A resolution in a carbonmonoxy R-state. On the basis of molecular dynamics simulations, a particular conformation had been predicted for the engineered Trp residue, and the lowered oxygen affinity had been attributed to a stabilization of the deoxy T-state interface by alpha 96Trp-beta 99Asp hydrogen bonds. Difference Fourier maps of the T-state structure clearly show that alpha 96Trp is in a conformation different from that predicted by the simulation, with its indole side chain directed away from the interface and into the central cavity. In this conformation, the indole nitrogen makes novel water-mediated hydrogen bonds across the T-state interface with beta 101Glu. We propose that these water-mediated hydrogen bonds are the structural basis for the lowered oxygen affinity of rHb(alpha 96Val-->Trp), and discuss the implications of these findings for future molecular dynamics studies and the design of Hb mutants.