Purification and characterization of the major cationic kallikrein inhibitor in bovine pituitary gland.

The presence of two types of kallikrein inhibitor (cationic and anionic inhibitors) was demonstrated in bovine pituitary gland. These kallikrein inhibitors were separated from the homogenate of bovine posterior pituitary by successive CM-Sephadex chromatography. The major cationic inhibitor was further purified to homogeneity by affinity chromatography using porcine pancreatic beta-kallikrein immobilized on Sepharose 4B and gel filtration. The complete amino acid sequence of this inhibitor was first determined, and it was shown to be a peptide of 58 residues with a calculated molecular weight of 6,511. The Ki value against bovine pituitary kallikrein was 6 x 10(-9) M. The cationic inhibitor was found to be identical with basic pancreatic trypsin inhibitor.

Amino acid sequence of the 8-kDa protein in photosystem I reaction center complex from a thermophilic cyanobacterium, Synechococcus elongatus.

The 8-kDa protein in Photosystem I (PS I) reaction center complex was isolated from a thermophilic cyanobacterium, Synechococcus elongatus, by SDS-polyacrylamide gel electrophoresis using TRIS-Tricine buffer system. The complete amino acid sequence of the protein was determined. The 8-kDa protein consisted of 73 amino acid residues giving a calculated molecular weight of 7,472. No significant sequence homology were observed with the known other small subunits in PS I reaction center complex, except for the 6.5-kDa protein in PS I from another thermophilic cyanobacterium, S. vulcanus. The 8-kDa protein was characteristically rich in hydrophobic amino acid residues, especially the content of leucine. These suggest that the 8-kDa subunit is an intrinsic structure component in PS I core complex for stabilization of the reaction center.

A variant database.

Variant biomacromolecules, either natural or artificially created, are proving to be useful in determining structure-function relationships. Research in this field would be facilitated by the compilation of data of variants into a central and widely available repository. The Variant Database acts as a repository for data concerning variant molecules. It complements the Biological Activity and the Physicochemical Property Databases as well as provides variant sequences.

Non-sequence databases for biological activity and physicochemical properties.

A biological activity database and a physicochemical property database are described. They are intended to complement the protein sequence database of PIR-International. The Biological Activity Database and the Physicochemical Property Database contain information regarding the biological activity and the physicochemical properties of proteins, respectively. In addition they also provide information about wild-type molecules with which information concerning variant molecules may be compared. Data on artificial variant molecules are stored in the Artificial Variant Database which is described separately.

N-terminal amino acid sequence analysis of small subunits of photosystem I reaction center complex from a thermophilic cyanobacterium, Synechococcus elongatus Nägeli.

Four small subunits (14, 13, 10, and 8 kDa) of the photosystem I reaction center complex were isolated from a thermophilic cyanobacterium Synechococcus elongatus and their N-terminal amino acid sequences determined. Sequence analysis of the 10-kDa subunit revealed that the distribution of cysteine residues, Cys-X-X-Cys-X-X-Cys-X-X-X-Cys-Pro, is characteristic of bacterial-type ferredoxins, and that its partial sequence is highly homologous to that deduced from the chloroplast gene frx A of liverwort. This indicates that the 10-kDa polypeptide is an apoprotein carrying two iron-sulfur centers, FA and FB, assigned as [4Fe-4S] clusters, which mediated the light-activated transfer of electrons from P700 in photosystem I reaction center complex to soluble ferredoxin. The amino acid sequence of the 14-kDa polypeptide also showed similarity to that of the 20-kDa polypeptide from spinach chloroplast that can be chemically crosslinked with soluble ferredoxin. Thus, the 14-kDa polypeptide appears to be the ferredoxin 'docking' protein.

Sensitization of Edman amino acid derivatives using the fluorescent reagent, 4-aminofluorescein.

The ability to analyze amino acid derivatives at the femtomole level is one of the most interesting challenges in the field of protein microsequencing. 2-Anilino-5-thiazolinone amino acids, obtained by Edman degradation, were quantitatively derivatized with fluorescent primary amines. The most fluorescent reagent tested was 4-aminofluorescein. The amino acid derivatives sensitized with this reagent were separated using reversed-phase high-performance liquid chromatography and identified at the 100 attomole level. Incorporation of this method into the operation of a conventional automated sequencer is also described.

Sensitization of amino acid derivatives obtained from Edman degradation with radioactively-labeled iodohistamine.

The minimum amount of proteins and peptides required for sequencing is constantly decreasing as more sensitive microsequencing methods are developed. The sensitization of and Edman degradation product is one such method. We took the 2-anilino 5-thiazolinone amino acid intermediates obtained from Edman degradation by conventional sequencing procedures, and quantitatively reacted them with a primary amine. The amine used was radioactive [125I]iodohistamine, which affords highly sensitive detection. The labeled amino acid derivatives were separated by thin layer chromatography. Ten femtomoles of a labeled derivative can be detected by autoradiography.