scholarly journals Regulation of tyrosinase in human melanocytes grown in culture.

1983 ◽  
Vol 97 (2) ◽  
pp. 480-488 ◽  
Author(s):  
R Halaban ◽  
S H Pomerantz ◽  
S Marshall ◽  
D T Lambert ◽  
A B Lerner
Keyword(s):  
Molecular Weight ◽  
Posttranslational Modification ◽  
Apparent Molecular Weight ◽  
Tyrosinase Activity ◽  
Unique Product ◽  
Biochemical Event ◽  
Human Melanocytes ◽  
Low Levels

Tyrosinase, the enzyme that controls the synthesis of melanin, is a unique product of melanocytes. Normal and malignant human melanocytes grown in culture were used to study the factors that regulate the expression of tyrosinase. Immunoprecipitation experiments showed that newly synthesized tyrosinase appeared as a protein with an apparent molecular weight of 70,000 that was processed to a protein with an apparent molecular weight of 80,000. Neither tunicamycin nor 2-deoxy-D-glucose inhibited this conversion, suggesting that O-glycosylation is the major biochemical event in the posttranslational modification of tyrosinase. Agents that stimulated the proliferation of normal melanocytes also stimulated tyrosinase activity. Melanocytes with low levels of tyrosinase activity synthesized less tyrosinase, processed the enzyme more slowly, and degraded it more rapidly than melanocytes with high levels of tyrosinase activity. We conclude that tyrosinase activity in cultures of human melanocytes derived from different donors is determined predominantly by its abundance.

Physico-Chemical Properties of Recombinant Desulphatohirudin

1990 ◽  
Vol 63 (03) ◽  
pp. 499-504 ◽  
Author(s):  
A Electricwala ◽  
L Irons ◽  
R Wait ◽  
R J G Carr ◽  
R J Ling ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Alpha Helix ◽  
Apparent Molecular Weight ◽  
Correlation Spectroscopy ◽  
Nmr Studies ◽  
Recombinant Hirudin ◽  
Physico Chemical ◽  
Recombinant Molecule

SummaryPhysico-chemical properties of recombinant desulphatohirudin expressed in yeast (CIBA GEIGY code No. CGP 39393) were reinvestigated. As previously reported for natural hirudin, the recombinant molecule exhibited abnormal behaviour by gel filtration with an apparent molecular weight greater than that based on the primary structure. However, molecular weight estimation by SDS gel electrophoresis, FAB-mass spectrometry and Photon Correlation Spectroscopy were in agreement with the theoretical molecular weight, with little suggestion of dimer or aggregate formation. Circular dichroism studies of the recombinant molecule show similar spectra at different pH values but are markedly different from that reported by Konno et al. (13) for a natural hirudin-variant. Our CD studies indicate the presence of about 60% beta sheet and the absence of alpha helix in the secondary structure of recombinant hirudin, in agreement with the conformation determined by NMR studies (17)

The Activation of Human Factor IX

1975 ◽  
Vol 33 (03) ◽  
pp. 553-563 ◽  
Author(s):  
B Østerud ◽  
K Laake ◽  
H Prydz
Keyword(s):  
Molecular Weight ◽  
Sodium Dodecyl ◽  
Apparent Molecular Weight ◽  
Factor Ix ◽  
Factor Vii ◽  
Activate Factor ◽  
Human Factor Ix ◽  
Factor Xia ◽  
Tissue Thromboplastin ◽  
Native Factor

SummaryThe activation of factor IX purified from human plasma has been studied. Factor XIa and kallikrein separately activated factor IX to factor IXa. In both cases factor IX a had an apparent molecular weight of about 42–45000 in sodium dodecyl sul-phate-polyacrylamide disc gel electrophoresis compared with a molecular weight of about 70000 for the native factor IX. The activation by XIa required Ca2+-ions whereas Ca2+-ions did not influence the activation by kallikrein. A mixture of tissue thromboplastin and factor VII or RusselPs-viper venom alone did not activate factor IX. Trypsin activated and plasmin inactivated factor IX.

Melanocyte-stimulating hormone and the regulation of tyrosinase activity in hair follicular melanocytes of the mouse

1986 ◽  
Vol 111 (2) ◽  
pp. 225-232 ◽  
Author(s):  
S. A. Burchill ◽  
A. J. Thody
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Hair Growth ◽  
Yellow Pigment ◽  
Tyrosinase Activity ◽  
Melanocyte Stimulating Hormone ◽  
Golden Yellow ◽  
Skin Explants ◽  
Low Levels ◽  
Old Mice

ABSTRACT Skin tyrosinase activity increases during hair growth in C3H–HeA*vy mice and reaches higher levels in young (30- to 35-day-old) mice when the hair follicular melanocytes synthesize the black pigment, eumelanin, than in older (6-month-old) mice when they produce the golden yellow pigment, phaeomelanin. To examine the regulation of the melanocytes at these different stages we have compared the effect of α-MSH and other agents that act, through cyclic AMP-dependent mechanisms, on skin tyrosinase activity in both young and old mice during hair growth, initiated by plucking. Daily administration of α-MSH, isoprenaline or theophylline increased coat darkness, and skin tyrosinase activity in the younger mice 7–9 days after plucking, but they were ineffective in the older mice. Similarly α-MSH, 8-bromo-cyclic AMP or theophylline increased tyrosinase activity in skin explants from the younger mice incubated for up to 24 h but had no effect in explants from older mice. Cyclic GMP had no effect on tyrosinase activity in skin explants from both young and old mice. It is suggested that whereas cyclic AMP-dependent mechanisms may operate to regulate tyrosinase activity in the hair follicular melanocytes of younger mice that produce eumelanin these systems may not operate in the older mice when these melanocytes synthesize phaeomelanin. Phaeomelanin synthesis, unlike that of eumelanin, may not depend upon tyrosinase and its regulation by cyclic AMP and this could explain the low levels of this enzyme in the skin and its failure to respond to α-MSH and other activators of the cyclic AMP system during periods of phaeomelanin production. J. Endocr. (1986) 111, 225–232

scholarly journals Nuclear matrix of HeLa S3 cells. Polypeptide composition during adenovirus infection and in phases of the cell cycle.

1977 ◽  
Vol 72 (1) ◽  
pp. 194-208 ◽  
Author(s):  
L D Hodge ◽  
P Mancini ◽  
F M Davis ◽  
P Heywood
Keyword(s):  
Cell Cycle ◽  
Molecular Weight ◽  
Nuclear Matrix ◽  
Apparent Molecular Weight ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Liver Nuclei ◽  
Hela S3 ◽  
Biochemical Analyses

A subnuclear fraction has been isolated from HeLa S3 nuclei after treatment with high salt buffer, deoxyribonuclease, and dithiothreitol. This fraction retains the approximate size and shape of nuclei and resembles the nuclear matrix recently isolated from rat liver nuclei. Ultrastructural and biochemical analyses indicate that this structure consists of nonmembranous elements as well as some membranous elements. Its chemical composition is 87% protein, 12% phospholipid, 1% DNA, and 0.1% RNA by weight. The protein constituents are resolved in SDS-polyacrylamide slab gels into 30-35 distinguishable bands in the apparent molecular weight range of 14,000 - 200,000 with major peptides at 14,000 - 18,000 and 45,000 - 75,000. Analysis of newly synthesized polypeptides by cylindrical gel electrophoresis reveals another cluster in the 90,000-130,000 molecular weight range. Infection with adenovirus results in an altered polypeptide profile. Additional polypeptides with apparent molecular weights of 21,000, 23,000, and 92,000 become major components by 22 h after infection. Concomitantly, some peptides in the 45,000-75,000 mol wt range become less prominent. In synchronized cells the relative staining capacity of the six bands in the 45,000-75,000 mol wt range changes during the cell cycle. Synthesis of at least some matrix polypeptides occures in all phases of the cell cycle, although there is decreased synthesis in late S/G2. In the absence of protein synthesis after cell division, at least some polypeptides in the 45,000-75,000 mol wt range survive nuclear dispersal and subsequent reformation during mitosis. The possible significance of this subnuclear structure with regard to structure-function relationships within the nucleus during virus replication and during the life cycle of the cell is discussed.

Apparent molecular weight of the substance P binding site in rat brain

1988 ◽  
Vol 152 (1-2) ◽  
pp. 171-174 ◽  
Author(s):  
Yoshihiro Nakata ◽  
Chie Hiraoka ◽  
Tomio Segawa
Keyword(s):  
Molecular Weight ◽  
Substance P ◽  
Binding Site ◽  
Rat Brain ◽  
Apparent Molecular Weight

Detection of inducible nitric oxide synthase inSchistosoma japonicumandS. mansoni

2004 ◽  
Vol 78 (1) ◽  
pp. 47-50 ◽  
Author(s):  
X.-C. Long ◽  
M. Bahgat ◽  
K. Chlichlia ◽  
A. Ruppel ◽  
Y.-L. Li
Keyword(s):  
Nitric Oxide ◽  
Molecular Weight ◽  
Inducible Nitric Oxide Synthase ◽  
Mouse Liver ◽  
Apparent Molecular Weight ◽  
Western Blots ◽  
Oxide Synthase ◽  
Host Tissues ◽  
Inducible Nitric Oxide

AbstractSchistosoma japonicumandS. mansoniwere tested for reactivity with an anti-inducible nitric oxide (iNOS) antibody and the distribution of iNOS was studied by immunofluorescent tests in different stages of the parasites. Reactivity was associated with the tegument in both larval schistosomes (sporocysts and cercariae) and eggs. With adult worms, the majority of the immunofluorescence was predominantly subtegumental inS. japonicumand parenchymal inS. mansoni. Fluorescence was also observed in host tissues (snails and mouse liver). In Western blots, the enzyme ofS. japonicumhad an apparent molecular weight of about 210 kDa. The possible role of worm and host iNOS in the parasite–host interrelation remains to be clarified.

scholarly journals Characterization of Trypsin Inhibitor in Florunner Peanut Seeds (Arachis hypogaea L.)1

1988 ◽  
Vol 15 (2) ◽  
pp. 81-84 ◽  
Author(s):  
E. M. Ahmed ◽  
J. A. Applewhite
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Arachis Hypogaea ◽  
Trypsin Inhibitor ◽  
Low Molecular Weight ◽  
Arachis Hypogaea L ◽  
Amino Acid Profiles ◽  
Low Levels

Abstract Florunner peanut seeds contained five trypsin isoinhibitors. Amino acid profiles of the trypsin inhibitors fraction showed high levels of aspartic acid, half-cystine and serine and low levels of histidine and tyrosine. The molecular weight of the inhibitor was 8.3 KDa. The presence of multiforms of this inhibitor, its low molecular weight and the high amount of half-cystine indicate that peanut trypsin inhibitor is of the Bowman-Birk type.

Partial characterization of cheese-ripening proteinases produced by the yeastKluyveromyces lactis

1983 ◽  
Vol 50 (4) ◽  
pp. 469-480 ◽  
Author(s):  
Paul A. Grieve ◽  
Barry J. Kitchen ◽  
John R. Dulley ◽  
John Bartley
Keyword(s):  
Molecular Weight ◽  
Kluyveromyces Lactis ◽  
Apparent Molecular Weight ◽  
Aminopeptidase Activity ◽  
Carboxypeptidase Y ◽  
Casein Hydrolysis ◽  
Cheese Ripening ◽  
Caseinolytic Activity ◽  
Proteinase A

SUMMARYAn extract ofKluyveromyces lactis416 and a β-galactosidase preparation (Maxilact 40000) contaminated with proteinase, showed similar pH profiles of caseinolytic activity. Similar modes of casein hydrolysis (κ-, > αs-, ≥ β-) were observed at pH 5·0 (the pH of Cheddar cheese), without detection of bitterness. The contaminated Maxilact preparation contained similar proteinase types to those detected in an autolysate ofK. lactis. Both the autolysate and the Maxilact preparation contained acid endopeptidase (proteinase A), serine endopeptidase (proteinase B) and serine exopeptidase (carboxypeptidase Y) activities. Some aminopeptidase activity was also detected in both preparations. There were some differences in apparent molecular weight and charge properties between proteinase A and B and carboxypeptidase Y from the 2 proteinase sources.

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