scholarly journals Proteins of the kidney microvillus membrane. Identification of subunits after sodium dodecylsullphate/polyacrylamide-gel electrophoresis

1976 ◽  
Vol 159 (2) ◽  
pp. 395-407 ◽  
Author(s):  
A G Booth ◽  
A J Kenny

The proteins of microvilli prepared from pig kidney were analysed by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. The typical pattern stained for protein revealed five major bands, four of which also stained for carbohydrate, and about 15 minor bands. For descriptive purposes the bands were designated numerically by their apparent molecular weights (X10(-3). Well-characterized proteins were identified with four of the five major bands. Dipeptidyl peptidase IV, a serine proteinase that may be specifically labelled with di-isopropyl [32P]phosphorofluoridate, was assigned to band 130. Aminopeptidase M was assigned to band 160, though when released from the membrane by a proteinase, this protein comprises three polypeptides each of lower apparent molecular weight than the native enzyme. Neutral endopeptidase can be assigned to band 95 and actin to band 42. The fifth major band (180) is an extrinsic glycoprotein that has not been identified with any microvillus enzyme activity. These four proteins contribute 21% of the microvillus-membrane protein. Kidney microvillus actin was characterized by a variety of properties and was similar to muscle actin. A computer analysis of the gel pattern indicates that it comprises 9.0% of the microvillus protein. Myosin is not present in the microvillus, but another protein associated with band 95, with properties that distinguish it from neutral endopeptidase, was tentatively identified as α-actinin. Alkaline phosphatase was identified as a monomeric polypeptide with an apparent molecular weight of 80000; it is a minor protein of the microvillus and is not discernible as a discrete band in the gel pattern. These and other results permit a model of the organization of the microvillus protein to be suggested. The computer program used has been deposited as Supplementary Publication SUP 50070 (12 pages) at the British Library Lending Division, Boston Spa. Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms given in Biochem. J. (1976) 153,5.

1981 ◽  
Vol 193 (3) ◽  
pp. 947-951 ◽  
Author(s):  
I A Braude ◽  
L S Lin ◽  
W E Stewart

Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis was used to characterize human leucocyte interferon (HuIFN-alpha) under reducing and non-reducing conditions. Under non-reducing conditions HuIFN-alpha possesses two size forms, but under reducing conditions (r-HuIFN-alpha) only one is observed. The apparent molecular weight of this one form varies with the concentration of 2-mercaptoethanol used. When r-HuIFN-alpha is permitted to reoxidize the bimodal configuration of HuIFN-alpha is restored. The size heterogeneity of native HuIFN-alpha can be eliminated by mild treatment with NaIO4 [HuIFN-alpha/IO4; Stewart II, Lin, Wiranowska-Stewart & Cantell (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 4200-4204]. The size of the HuIFN-alpha/IO4 increases after treatment with 2-mercaptoethanol (r-HuIFN-alpha/IO4) and the apparent molecular weight of this component also varies with the concentration of 2-mercaptoethanol used. In the case of r-HuIFN-alpha the single peak observed apparently originates from both the higher- and lower-molecular-weight components.


1977 ◽  
Vol 55 (9) ◽  
pp. 958-964 ◽  
Author(s):  
M. P. C. Ip ◽  
R. J. Thibert ◽  
D. E. Schmidt Jr.

Cysteine-glutamate transaminase (cysteine aminotransferase; EC 2.6.1.3) has been purified 149-fold to an apparent homogeneity giving a specific activity of 2.09 IU per milligram of protein with an overall yield of 15%. The isolation procedures involve the preliminary separation of a crude rat liver homogenate which was submitted sequentially to ammonium sulfate fractionation, TEAE-cellulose column chromatography, ultrafiltration, and isoelectrofocusing. The final product was homogenous when examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS). A minimal molecular weight of 83 500 was determined by Sephadex gel chromatography. The molecular weight as estimated by polyacrylamide gel electrophoresis in the presence of SDS was 84 000. The purified enzyme exhibited a pH optimum at 8.2 with cysteine and α-ketoglutarate as substrates. The enzyme is inactivated slowly when kept frozen and is completely inactivated if left at room temperature for 1 h. The enzyme does not catalyze the transamination of α-methyl-DL-cysteine, which, when present to a final concentration of 10 mM, exhibits a 23.2% inhibition of transamination of 30 mM of cysteine. The mechanism apparently resembles that of aspartate-glutamate transaminase (EC 2.6.1.1) in which the presence of a labile hydrogen on the alpha-carbon in the substrate is one of the strict requirements.


1973 ◽  
Vol 51 (11) ◽  
pp. 1551-1555 ◽  
Author(s):  
Tony C. M. Seah ◽  
A. R. Bhatti ◽  
J. G. Kaplan

At any stage of growth of a wild-type bakers' yeast, some 20% of the catalatic activity of crude extracts is not precipitable by means of antibody prepared against the typical catalase (catalase T), whose purification and properties have been previously described. Some of this catalatic activity is due to the presence of an atypical catalase (catalase A), a heme protein, with a molecular weight estimated as 170 000 – 190 000, considerably lower than that of the usual catalases (225 000 – 250 000). Preparations of catalase A were found to be homogeneous in the analytical ultracentrifuge and in polyacrylamide gel electrophoresis. Its subunit molecular weight, determined from its iron content, was 46 500, virtually the same as that of the major band obtained in gel electrophoresis in the presence of sodium dodecyl sulfate, suggesting that the native protein is tetrameric. Its specific activity is in the range of those reported for other typical catalases.


1989 ◽  
Vol 40 (3) ◽  
pp. 675 ◽  
Author(s):  
DJ Tucker ◽  
AHF Hudson ◽  
A Laudani ◽  
RC Marshall ◽  
DE Rivett

The proteins from a range of cashmere, mohair, angoratcashmere crossbred and wool fibre samples were extracted at pH 8 with 8 M urea containing dithiothreitol, and were then radiolabelled by S-carboxymethylation using iodo(2-14C) acetate. The proteins from each sample were examined by two dimensional polyacrylamide gel electrophoresis in which the separation in the first dimension was according to charge at pH 8.9 and in the second dimension according to apparent molecular weight in the presence of sodium dodecyl sulfate. After electrophoresis the proteins were detected by fluorography. Protein differences in keratin samples from some individual goats existed, although the overall protein patterns were similar. None of the differences were consistent with any one goat fibre type. The protein patterns obtained for fibre samples from individual cashmere goats showed some differences when compared to those found for commercial blends from the same country of origin, indicating that blending can mask any animal-to-animal variation. While the electrophoretic technique does not unequivocally distinguish between cashmere, mohair and angora/cashmere crossbred fibres it does differentiate between wool and goat fibres.


1981 ◽  
Vol 195 (2) ◽  
pp. 389-397 ◽  
Author(s):  
D A Wiginton ◽  
M S Coleman ◽  
J J Hutton

Adenosine deaminase was purified 3038-fold to apparent homogeneity from human leukaemic granulocytes by adenosine affinity chromatography. The purified enzyme has a specific activity of 486 mumol/min per mg of protein at 35 degrees C. It exhibits a single band when subjected to sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, non-denaturing polyacrylamide-gel electrophoresis and isoelectric focusing. The pI is 4.4. The enzyme is a monomeric protein of molecular weight 44000. Both electrophoretic behaviour and molecular weight differ from those of the low-molecular-weight adenosine deaminase purified from human erythrocytes. Its amino acid composition is reported. Tests with periodic acid-Schiff reagent for associated carbohydrate are negative. Of the large group of physiological compounds tested as potential effectors, none has a significant effect. The enzyme is specific for adenosine and deoxyadenosine, with Km values of 48 microM and 34 microM respectively. There are no significant differences in enzyme function on the two substrates. erythro-9-(2-Hydroxy non-3-yl) adenine is a competitive inhibitor, with Ki 15 nM. Deoxycoformycin inhibits deamination of both adenosine and deoxyadenosine, with an apparent Ki of 60-90 pM. A specific antibody was developed against the purified enzyme, and a sensitive radioimmunoassay for adenosine deaminase protein is described.


1981 ◽  
Vol 195 (3) ◽  
pp. 545-560 ◽  
Author(s):  
Heinz Fankhauser ◽  
Jerome A. Schiff ◽  
Leonard J. Garber

Extracts of Chlorella pyrenoidosa, Euglena gracilis var. bacillaris, spinach, barley, Dictyostelium discoideum and Escherichia coli form an unknown compound enzymically from adenosine 5′-phosphosulphate in the presence of ammonia. This unknown compound shares the following properties with adenosine 5′-phosphoramidate: molar proportions of constituent parts (1 adenine:1 ribose:1 phosphate:1 ammonia released at low pH), co-electrophoresis in all buffers tested including borate, formation of AMP at low pH through release of ammonia, mass and i.r. spectra and conversion into 5′-AMP by phosphodiesterase. This unknown compound therefore appears to be identical with adenosine 5′-phosphoramidate. The enzyme that catalyses the formation of adenosine 5′-phosphoramidate from ammonia and adenosine 5′-phosphosulphate was purified 1800-fold (to homogeneity) from Chlorella by using (NH4)2SO4 precipitation and DEAE-cellulose, Sephadex and Reactive Blue 2–agarose chromatography. The purified enzyme shows one band of protein, coincident with activity, at a position corresponding to 60000–65000 molecular weight, on polyacrylamide-gel electrophoresis, and yields three subunits on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of 26000, 21000 and 17000 molecular weight, consistent with a molecular weight of 64000 for the native enzyme. Isoelectrofocusing yields one band of pI4.2. The pH optimum of the enzyme-catalysed reaction is 8.8. ATP, ADP or adenosine 3′-phosphate 5′-phosphosulphate will not replace adenosine 5′-phosphosulphate, and the apparent Km for the last-mentioned compound is 0.82mm. The apparent Km for ammonia (assuming NH3 to be the active species) is about 10mm. A large variety of primary, secondary and tertiary amines or amides will not replace ammonia. One mol.prop. of adenosine 5′-phosphosulphate reacts with 1 mol.prop. of ammonia to yield 1 mol.prop. each of adenosine 5′-phosphoramidate and sulphate; no AMP is found. The highly purified enzyme does not catalyse any of the known reactions of adenosine 5′-phosphosulphate, including those catalysed by ATP sulphurylase, adenosine 5′-phosphosulphate kinase, adenosine 5′-phosphosulphate sulphotransferase or ADP sulphurylase. Adenosine 5′-phosphoramidate is found in old samples of the ammonium salt of adenosine 5′-phosphosulphate and can be formed non-enzymically if adenosine 5′-phosphosulphate and ammonia are boiled. In the non-enzymic reaction both adenosine 5′-phosphoramidate and AMP are formed. Thus the enzyme forms adenosine 5′-phosphoramidate by selectively speeding up an already favoured reaction.


1984 ◽  
Vol 44 (2) ◽  
pp. 117-123 ◽  
Author(s):  
N. K. Singh ◽  
K. W. Shepherd

SUMMARYThe gene(s) controlling the high-molecular-weight glutelin subunits in rye (designated as Glu-Rl) was mapped with respect to the centromere using a 1RL-1DS wheat-rye translocation line and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Analysis of 479 seeds from test-crosses between a 1R/1RL-1DS heterozygote and the cultivar India 115, revealed 14·6% aneuploid and 3·95% recombinant progeny. Excluding the aneuploids, this locus was calculated to be 4·65 ± 1·04 cM from the centromere on the long arm of chromosome 1R, which is comparable to the position of the homoeologous loci in wheat and barley.


1974 ◽  
Vol 141 (2) ◽  
pp. 413-418 ◽  
Author(s):  
David J. Wright ◽  
Donald Boulter

Zonal isoelectric precipitation was shown to be an effective method for the preparation of legumin which was homogeneous as judged by ultracentrifugation and polyacrylamide-gel electrophoresis. The subunit structure of legumin was investigated by preparative sodium dodecyl sulphate–polyacrylamide-gel electrophoresis and ion-exchange chromatography in urea. Five distinct subunits, of which two were acidic (α) and had a molecular weight of 37000, and three were basic (β) with molecular weights of 20100, 20900 and 23800, were identified. The α and β subunits were present in equimolar amounts in the legumin molecule and, in view of this and molecular-weight considerations, an α6β6 subunit model was proposed for legumin.


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