Enzymatic properties of thiol-dependent serine proteinase of Bacillus intermedius 3-19.

Effects of a thiol-dependent serine proteinase of Bacillus intermedius on peptide substrates and insulin B-chain were studied. The enzyme preferably splits peptide bonds formed by carboxyl groups of hydrophobic amino acids. Ca2+ increases the thermal stability of the proteinase significantly. The kinetic characteristics of hydrolysis of Z-Ala-Ala-Leu-pNA by this enzyme was determined as K(m) = 1.25 mM and kcat = 0.15 sec-1. The enzyme has high stability to DMFA and isopropanol, and is able to catalyze peptide bond synthesis.

[Biosynthesis of alkaline extracellular proteinases in Bacillus intermedius]. / Biosintez shchelochnoi vnekletochnoi proteinazy Bacillus intermedius.

The conditions for growth and serine proteinase biosynthesis were studied in the batch culture of Bacillus intermedius. The synthesis of the enzyme was found to be inhibited by glucose and by the amino acid mixture and activated by the addition of organic compounds-casein and gelatin-to the medium. Inorganic phosphate in the medium increased the enzyme yield. The enzyme activity was shown to be twofold higher upon the addition of corn extract (1.8%) in the medium than in the medium with meat peptone (1.7-2.2%) and inorganic phosphate (0.28-0.30 miligram).

[Secreted serine proteinase from the spore-forming bacteria Bacillus intermedius 3-19]. / Sekretiruemaia serinovaia proteinaza sporoobrazuiushchikh bakterii Bacillus intermedius 3-19.

Extracellular serine proteinase has been isolated from the cultural medium of Bacillus intermedius 3-19 using CM-cellulose chromatography and affinity chromatography on bacitracin-Sepharose. The specificity of the proteinase with a wide range of natural and synthetic substrates has been investigated. The greatest activity was observed with tripeptides containing C-terminal Leu or Phe. The enzyme was completely inhibited by diisopropylfluorophosphate and partly inhibited by thiol-specific reagents. It is concluded that B. intermedius proteinase is a thiol-dependent serine proteinase pertaining to the subtilisin group. The amino acid composition of the enzyme has been determined. The enzyme contains one to three 1/2 cysteine residues, one of which is supposedly a Cys residue. The N-terminal amino acid sequences of the protein is AQTVPYGIPQIKAPA-.

[Alkaline extracellular proteinase from Bacillus intermedius. Isolation, purification, and some properties of the enzyme]. / Shchelochnaia vnekleochnaia proteinaza Bacillus intermedius. Vydelenie, ochistka i nekotorye svoistva fermenta.

Extracellular alkaline proteinase was isolated from the Bacillus intermedius culture medium. The enzyme was purified by ion-exchange chromatography 200-fold to apparent homogeneity and has a specific activity of 950 u./mg. The proteinase was maximally active at pH 10, 50 degrees C and is stable at pH 6.3-11.0. EDTA, o-phenanthroline or p-chloromercuribenzoate did not affect the enzyme activity, while phenylmethylsulfonyl fluoride inhibited it by 95-97%. It was concluded that the enzyme is subtilisin-like and belongs to the serine proteinase family of Bacilli.

Adverse reaction to intravenous gadoteridol.

Moderate and severe anaphylactoid reactions--while extremely rare--have been reported in association with intravenous administration of gadopentetate dimeglumine. There has been no similar experience related to use of the newly released magnetic resonance (MR) imaging contrast agent gadoteridol. The authors describe a case of vasovagal response and anaphylactoid reaction during intravenous administration of gadoteridol. MR users should be aware of the potential for adverse effects to occur in association with use of gadoteridol and be prepared by implementing appropriate observation procedures for patients receiving this as well as other MR contrast agents. In addition, physiologic monitoring devices and resuscitation equipment should be readily available in the clinical MR setting for proper treatment of patients who may experience moderate to severe adverse reactions.

[Mechanisms of charge separation in photosynthetic reaction centers]. / O mekhanizmakh razdeleniia zariada v fotosinteticheskom tsentre.

Light quanta absorbed by means of light -- absorbing matrix of pigment molecules are transferred with several special molecules forming the photoreaction centre (PhRC). The following conditions should be met for an effective storage of electron excitation energy in PhRC resulting from charge division: 1) electron transfer from donor to acceptor should proceed in the time less than life time of the initial excited state; 2) this transfer ought to be irreversible to a sufficient degree; 3) the less possible portion of the excitation energy should be lost in this process. Simultaneous fulfilment of these conditions is concerned with certain difficulties. Two means for overcoming these difficulties (multistage process and contribution of conformation degree of freedom) are proposed. Their realization at various stages of charge division involves probable mechanism of PhPC functioning.