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Biomedical subjects

K Murai

Publications and source records attributed to K Murai.

At least 217 records · Page 12Linked to original sources
PubMed1980

Purification and properties of deoxyribonuclease II from human urine.

The acid deoxyribonucleases [DNase II; EC 3.1.4.6] in human urine were purified approximately 400- to 500-fold by phosphocellulose chromatography, gel filtration on Sephadex G-75 and isoelectric focusing, with a total recovery of 22%. The enzymes were present in a least three forms with different isoelectric points, pHs 6.4, 6.6, and 6.8. However, other properties were essentially similar. The enzymes did not require divalent cations for activity, and the optimal pHs were at 5.1 to 5.3 in 33 mM acetate buffer. They had a molecular weight of around 36,000, as estimated by gel filtration on Sephadex G-75. The enzymes were endonucleases which hydrolyzed native, double-stranded DNA about 5 to 15 times faster than thermally denatured DNA. The products formed from native DNA were 3'-phosphoryl- and 5'-hydroxy-terminated oligonucleotides. The average chain length of the limit digests with these enzymes was approximately 11 to 15, and the major fragments were longer than pentanucleotides. The final preparations were free of nonspecific acid and alkaline phosphatases and phosphodiesterase, but contained contaminating ribonuclease activity.

Deoxyribonucleases↗
PubMed1978

Purification and properties of deoxyribonuclease from human urine.

The DNAase in human urine was purified about 30-fold with a recovery of 28%. This involved DEAE-cellulose and phosphocellulose chromatography steps and gel filtration on Sephadex G-75. The enzyme required divalent cations such as Co2+, Mg2+, Mn2+ and Zn2+ for activity, but Ca2+, Cu2+ and Fe2+ were ineffective. EDTA and G-actin inhibited the reaction. The maximum activity was observed at pH 5.5 in acetate buffer plus Co2+ or Mg2+ and Ca2+. It had a molecular weight of approximately 38 000, estimated by gel filtration on Sephadex G-75 and isoelectric point of around pH 3.9. The enzyme is an endonuclease which hydrolyzes native, double-stranded DNA about 3 to 4 times faster than thermally denatured DNA to produce 5'-phosphoryl- and 3'-hydroxyl-terminated oligonucleotides. The final preparation was free of non-specific acid and alkaline phosphatases, phosphodiesterase and ribonuclease activities.

Chromatography, Gel↗
PubMed1978

Purification and properties of acid ribonucleases in human serum and leukocytes.

Acid RNase was purified from normal human serum about 2400-fold by chromatography on phosphocellulose and Sephadex G-75 and rechromatography on Sephadex G-75. Assayed with yeast RNA as substrate, the enzyme showed the maximal activity at about pH 6.5 with sodium phosphate buffer. The reaction was activated by Na+, K+, and spermine, but it was not affected greatly by Mg2+, Co2+, and EDTA. Ca2+, Fe2+, Zn2+, and Cu2+ inhibited the reaction. Among the synthetic substrates examined, the enzyme preferentially hydrolyzed pyrimidine nucleotides, with a higher affinity for polycytidylate than for polyuridylate. The enzyme was thermolabile, but it stabilized with bovine plasma albumin. The molecular weight was approximately 15,000, estimated gel filtration on Sephadex G-75, and its isoelectric pH was above 11.0. From normal human leukocytes, acid RNase was purified about 400-fold by the same procedure described previously except that rechromatography on Sephadex G-75 was omitted. The properties of leukocytic RNase were found to be similar to those of serum acid RNase, but the latter enzyme differed in substrate specificity substantially from leukocytic RNase, preferring polyuridylate to polycytidylate. This evidence shows that serum RNase is not of leukocytic origin under normal physiological conditions.

Chromatography, Gel↗
PubMed1978

Serum acid ribonuclease in myelogenous leukemia.

Acid and alkaline RNase activities in serum were measured with yeast RNA as the substrate in normal subjects and in leukemic patients pretreatment and posttreatment, and the acid/alkaline ratios of activities were 0.63 +/- 0.08 (S.D.) (N, 12), 2.28 +/- 0.82 (N, 8), and 0.60 +/- 0.13 (N, 9), respectively. The mean value for the ratio in the pretreated leukemia was significantly higher than that in the other 2 groups (p less than 0.01). By separating these acid and alkaline RNases from normal and leukemic sera by phosphocellulose chromatography, it was further confirmed that acid RNase alone increased markedly in leukemic serum. From serum and leukocytes of leukemic patients, acid RNases were purified about 2000-fold and 300-fold, respectively, by phosphocellulose and Sephadex G-75 chromatography. Both enzymes displayed properties nearly identical with those of normal serum and leukocytes, except that leukemic serum acid RNase had about a 2.4-fold greater affinity for polyuridylate than for polycytidylate as substrate, in contrast to normal serum acid RNase that degraded polycytidylate exclusively. On the other hand acid RNases from serum leukocytes of leukemia showed a similar substrate preference. These results suggest that the high RNase levels of leukemic sera are due to an excessive leakage of acid RNase into the blood stream from abnormal leukocytes.

Adult↗
PubMed1977

Purification and properties of urinary alkaline ribonucleases from patients with nephrotic syndrome.

Four urinary alkaline ribonucleases (RNase, EC 3.1.4.22) were purified from patients with nephrotic syndrome using phosphocellulose, DEAE-cellulose and Sephadex G-75 chromatographiy. These enzymes were designated as RNases 1--4, respectively, in order of elution on phosphocellulose chromatography. The respective purification of each fraction was 41-, 23-, 34- and 27-fold with a total recovery of 25%. The pH optima of these RNases were around 8.5 with Tris/HCl buffer and the reaction was activated by mono- and divalent cations, such as Na+, K+, Mg2+ and Ca2+, but inhibited by Fe2+, Cu2+ and Zn2+. EDTA had little effect on the velocity of reaction. The molecular weights of RNases 1--4 were estimated by gel filtration as 45 000, 32 000, 20 000, and 13 000, respectively. Each enzyme hydrolyzed pyrimidine nucleotides preferentially with higher affinity for poly(C) than poly (U) as determined with synthetic polymers and was free from other nucleolytic enzymes. The patients with renal disorders excreted one to four RNases in urine and the number of enzymes increased as the concentration of urinary protein increased. On the other hand, normal subjects excreted a single fraction essentially identical to RNase 1.

Adolescent↗
PubMed1976

Purification and properties of alkaline ribonuclease from human serum.

1. Five alkaline ribonucleases (EC 3.1.4.22) were purified about 140- to 1900-fold from human serum by phosphocellulose and DEAE-cellulose chromatographies and Sephadex G-75 filtration, with a total recovery of 22%. These were designated as RNAases 1-5. 2. Optimum activities were observed at pH 8.5-8.7 for RNAases 1-4, and at pH 7.5 for RNAase 5. The molecular weights of these enzymes were estimated by gel filtration as 45 000, 32 000, 20 000, 13 000 and 8500, respectively. 3. These RNAases were found to be heat-labile proteins but are markedly stabilized with bovine plasma albumin. The reaction was activated by Na+, K+, Mg2+ and Ca2+, and inhibited by Co2+, Fe2+, Cu2+ and Zn2+. EDTA had little effect on the velocity of the reaction. Spermine caused 2- to 7-fold activation. 4. Among the substrates examined, these RNAases preferentially hydrolyzed pyrimidine bodies and except for RNAase 5 had a higher affinity for poly(C) than poly(U) as substrate. Each enzyme was free from other nucleolytic enzymes and hydrolyzed only RNA.

Chromatography, DEAE-Cellulose↗
PubMed1975

Vectorcardiographic findings in concentric and eccentric left ventricular hypertrophy as determined by angiocardiograms. 1. Preliminary report.

In forty-one patients with various heart diseases including 29 with LVH, the vectorcardiograms of Frank system and angiocardiographic findings correlated minutely. Based on the left ventricular wall thickness in end-diastole, left ventricular end-diastolic volume, and the length of the long axis of the left ventricle obtained in angiocardiograms, typical left ventricular hypertrophy was classified into types 1a, 1b, 2a, 2b anatomically. The vectorcardiograms in these 4 types represented different patterns with regard to the QRS and T loops respectively. The QRS voltage in the left ventricular hypertrophy closely correlated to the left ventricular wall thickness in end-diastole, the left ventricular end-diastolic volume, and the left ventricular mass. Marked ST and T changes in the left ventricular concentric hypertrophy characterized by increase in wall thickness without definite chamber enlargement may be closely related to the abnormal muscle state with the increased left ventricular wall thickness, the probably due to relative hypoxia in origin. The Q loop of patients with severe left ventricular concentric hypertrophy was definitely differentiated from that of most patients with the pure left ventricular eccentric hypertrophy which was characterized by chamber enlargement with usually slight thickening of the wall. A possible mechanism regarding inconspicuous or prominent Q loops in both concentric and eccentric LVH was presented. An important factor of the delay of the time of occurrence of the spatial R vector in the left ventricular eccentric hypertrophy is the greater distance of the intraventricular conducting pathways caused by the left ventricular dilatation. By means of assessing the vectorcardiogram of the left ventricular hypertrophy, relatively exact anatomy of the left ventricular hypertrophy can be determined.

Adolescent↗