Evidence for retention of biological activity of a non-heme iron enzyme adsorbed on a silver colloid: a surface-enhanced resonance Raman scattering study

The structure and catalytic properties of the enzyme (E) chlorocatechol dioxygenase (CCD) adsorbed on a citrate-reduced silver colloid are analyzed by surface-enhanced resonance Raman spectroscopy (SERRS). This is the first SERRS study of a non-heme metalloenzyme. It is demonstrated that the native conformation of CCD is retained in the adsorbed state by comparison of resonance Raman scattering (RRS) from CCD in solution with SERRS from CCD adsorbed on the silver colloid. Both spectra show clear evidence of vibrational bands typical of iron-tyrosinate proteins. Furthermore, it is demonstrated that adsorbed CCD retains 60-85% of its enzymatic activity in the reaction of catechol substrate (S) with O2 to give the dioxygenated product (P) cis,cis-muconate. This is accomplished by enzyme assays of Ag-adsorbed CCD and comparison of the SERRS of Ag-adsorbed enzyme-substrate (ES) complex under anaerobic conditions with that of Ag-adsorbed ES in the presence of dioxygen. The SERRS difference spectrum, ES(aerobic)--ES(anaerobic), shows clear evidence for the appearance of the vibrational modes of adsorbed product. The analogous SERR difference spectroscopy experiment is also carried out for the enzyme-inhibitor (EI) complex of CCD with tetrachlorocatechol (TCC). Slow turnover of CCD-TCC is observed by SERRS on exposure to dioxygen which is consistent with the slow rate of turnover of TCC by CCD in solution.     

HLA antigens in three Siberian populations

The biological responses of the heme biosynthesis pathway in male workers moderately exposed to lead are discussed in relation to the concentration of lead in the blood. The level of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) activity in the group of lead-exposed workers was remarkably reduced while the level of erythrocyte protoporphyrin (Proto) in them was strikingly increased, compared to normal levels. On the other hand, the amounts of hemoglobin (Hb) and urinary delta-aminolevulinic acid (ALA) in the group of lead-exposed workers kept the normal levels. In the workers moderately exposed to lead, the log of erythrocyte Proto level was closely correlated to the blood lead level and the sensitivity of the Proto test was almost equal to that of erythrocyte ALA-D test. It was observed that the erythrocyte Proto was remarkably increased even in lead-exposed workers whose ALA excretion into the urine was in the range of normal level.     

Regulation of the interferon-inducible protein kinase PKR and (2''-5'')oligo(adenylate) synthetase by a catalytically inactive PKR mutant through competition for double-stranded RNA binding

This study evaluated the long-term effect of an ultrasonic toothbrush used as part of a daily oral hygiene regimen on supragingival plaque, gingivitis, and gingival bleeding. Compared with a conventional toothbrush, the ultrasonic toothbrush was significantly more effective in reducing plaque formation (p < 0.05), removing plaque (p < 0.05), and reducing gingivitis (p < 0.05) during the 6-month study period.     

Purulent infection and sepsis in surgical patients

The problems of pathogenesis, clinic and treatment of general purulent infection and sepsis are discussed. 1045 patients with different purulent diseases were observed by the author. Sepsis was diagnosed in 18 patients, that made 1.7 per cent to a total number of observations. Among these septic patients 8 patients died.