Structure-assisted redesign of a protein-zinc-binding site with femtomolar affinity.

We have inserted a fourth protein ligand into the zinc coordination polyhedron of carbonic anhydrase II (CAII) that increases metal affinity 200-fold (Kd = 20 fM). The three-dimensional structures of threonine-199-->aspartate (T199D) and threonine-199-->glutamate (T199E) CAIIs, determined by x-ray crystallographic methods to resolutions of 2.35 Angstrum and 2.

Structural consequences of redesigning a protein-zinc binding site.

In order to probe the structural importance of zinc ligands in the active site of human carbonic anhydrase II (CAII), we have determined the three-dimensional structures of H94C (in metal-bound form), H94C-BME (i.e., disulfide-linked with beta-mercaptoethanol), H94A, H96C, H119C, and H119D variants of CAII by X-ray crystallographic methods at resolutions of 2.

The triple-helical region of human type XIX collagen consists of multiple collagenous subdomains and exhibits limited sequence homology to alpha 1(XVI).

We previously isolated a clone from a human rhabdomyosarcoma (RH) cDNA library coding for a collagen chain different from those constituting the 18 reported types (Myers, J. C., Sun, M.

Structural and functional importance of a conserved hydrogen bond network in human carbonic anhydrase II.

Amino acid substitutions at Thr199 of human carbonic anhydrase II (CAII) (Thr199-->Ser, Ala, Val, and Pro) were characterized to investigate the importance of a conserved hydrogen bonding network. The three-dimensional structures of azide-bound and sulfate-bound T199V CAIIs were determined by x-ray crystallographic methods at 2.25 and 2.

Structure of an engineered His3Cys zinc binding site in human carbonic anhydrase II.

X-ray crystallographic analysis of the Thr-199-->Cys (T199C) variant of human carbonic anhydrase II reveals the first high-resolution structure of an engineered zinc coordination polyhedron in a metalloenzyme. In the wild-type enzyme, Thr-199 accepts a hydrogen bond from zinc-bound hydroxide; in the variant, the polypeptide backbone is sufficiently plastic to permit Cys-199 to displace hydroxide ion and coordinate to zinc with nearly perfect coordination stereochemistry. Importantly, the resulting His3-Cys-Zn2+ motif binds zinc more tightly than the wild-type enzyme [Kiefer, L.

Bronchiolitis obliterans organizing pneumonia and rheumatoid arthritis.

The case of a 68-year-old woman who presented with dyspnea and upper lobe pulmonary infiltrates and shortly thereafter developed seropositive, erosive polyarticular rheumatoid arthritis (RA) is presented. An open-lung biopsy to evaluate progression of infiltrates showed bronchiolitis obliterans-organizing pneumonia (BOOP). Both lung and articular disease responded rapidly to corticosteroid therapy.

Purification and characterization of Klebsiella aerogenes UreE protein: a nickel-binding protein that functions in urease metallocenter assembly.

The Klebsiella aerogenes ureE gene product was previously shown to facilitate assembly of the urease metallocenter (Lee, M.H., et al.

Human cDNA clones transcribed from an unusually high-molecular-weight RNA encode a new collagen chain.

Human collagen (COL) cDNA clones were isolated from a library representing transcripts synthesized by an established rhabdomyosarcoma (RH) cell line. The 0.6-kb insert of the first isolate encodes a discontinuous collagenous sequence not homologous to type I-XVI COL chains.

The contribution of halogen atoms to protein-ligand interactions.

The three-dimensional structure of para-fluoro-D-phenylalanine (PFF) in its complex with the zinc protease carboxypeptidase A (CPA) has been determined at 2.0 A resolution by X-ray crystallographic methods. The structure reveals that the para-fluorobenzyl side chain of the inhibitor is buried in the S'1 hydrophobic pocket of the enzyme.

Hydrogen bond stereochemistry in protein structure and function.

Fifty high resolution protein structures from the Brookhaven Protein Data Bank have been analyzed for recurring motifs in hydrogen bond stereochemistry. Although an exhaustive analysis of hydrogen bond statistics has been presented by Baker & Hubbard, a detailed stereochemical analysis of classical donor (N-H, O-H, or S-H) and acceptor (N:, O:, or S:) structure within proteins is lacking. Here, we describe the preferential hydrogen bond stereochemistry for the side-chains of glutamate and aspartate (carboxylate), glutamine and asparagine (carboxamide), arginine (guanidinium), histidine (imidazole/imidazolium), tryptophan (indole), tyrosine (phenolic hydroxyl), lysine (ammonium), serine and threonine (alkyl hydroxyl), cysteine (thiol), methionine (thioether) and cystine (disulfide).

Adrenal hemorrhage in the newborn with evidence of bleeding while in utero.

A case is reported of bilateral hemorrhagic adrenal cysts in a newborn. Evaluation of the patient included x-rays of the abdomen, excretory urography, retrograde pyelography and sonography. The presence of a faint calcification in the region of the right adrenal at birth and further progression of calcification in the same area suggest that some initial bleeding occurred in utero.

Aneurysm of a polar renal artery.

A patient with a saccular aneurysm arising from the left superior polar renal artery is presented together with a review of two further reports from the literature. The importance of selective arteriography and the interpretation of the "naked calyx" sign in the diagnosis of supernumerary renal arteries has been emphasized. We feel that this is the only report of an aneurysm of a polar artery successfully treated by excision and end-to-end arterial anastomosis.