摘要:

AbstractEndotoxin and laminarin activated prophenoloxidase in the plasma ofManduca sextahemolymph. Diisopropylfluorophosphate inhibited this activation, suggesting the presence of a serine protease in the activation cascade. Exogenously added proteases such as pronase, chymotrypsin, subtilisin, and thermolysin also activated prophenoloxidase inManducaplasma. However, these enzymes did not cause any detectable activation of partially purified prophenoloxidase. Thermolysin and subtilisin mediated activation of prophenoloxidase was inhibited byp‐nitrophenyl‐p′‐guanidobenzoate. Similarly, benzamidine inhibited prophenoloxidase activation catalyzed by thermolysin. Activity measurements reveal the activation of a serine protease prior to prophenoloxidase activation. These results indicate the presence of a precursor form for the serine protease which is responsible for prophenoloxidase activation inManduca sextahe

ISSN:0739-4462    

DOI:10.1002/arch.940050102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractIncubation of test proteins with horseradish peroxidase in the presence of hydrogen peroxide and a catechol resulted in polymerization and precipitation of test proteins. SDS‐PAGE readily revealed the generation of dimers, trimers, and higher oligomers in the reaction mixture. With the exception of 3,4‐dihydroxyphenylalanine, dopamine, and norepinephrine, most other catechols tested participated in protein polymerization. The inability of these three catechols to accomplish polymerization is attributed to their high rate of intramolecular cyclization, which results in melanin formation. Radioactive studies with [3H]N‐acetyldopamine clearly reveal both intermolecular and intramolecular cross‐linking of test proteins by peroxidase. Based on these studies a possible mechanism for sclerotization and the biological significance of peroxidase in cuticle is di

ISSN:0739-4462    

DOI:10.1002/arch.940050103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractPhosphoproteins were examined by electrophoresis and autoradiography in fractions of tick salivary glands. When whole salivary glands were preincubated in32Pi, then stimulated by 10 μM dopamine and subsequently fractionated, substantial phosphate was incorporated into 45,000‐, 47,000‐, and 62,000‐dalton proteins of the plasma membrane‐rich 11,500g pellet and 100,000g supernatant. When tissue homogenates were incubated in [γ‐32P] ATP prior to subcellular fractionation, the 62,000‐, 47,000‐, and 45,000‐dalton proteins were enhanced by cyclic AMP in all fractions and were most prominent in the membrane‐rich 11,500g fraction. Phosphoproteins of the same molecular masses were also found in the 11,500g pellet and 100,000g supernatant when labelled with [γ‐32P] ATP i

ISSN:0739-4462    

DOI:10.1002/arch.940050104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractInTribolium castaneumadults, sublethal doses of 1 and 2 ppm permethrin and 300 ppm malathion led to significant changes in amylase, trehalase, acid phosphatase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and isocitrate dehydrogenase activities. Malathion at 150 ppm did not affect phosphatases and lactate dehydrogenase. Both malathion and permethrin significantly increased cholinesterase activity. Mixing of the two insecticides resulted in antagonistic action with reference to various enzymatic activities. Glucose and glycogen contents were at first mobilized for energy supply under insecticidal stress conditions followed by lipid and cholesterol. Soluble protein, total protein, free amino acids, and urea contents remained unaltered under all experimental conditions.

ISSN:0739-4462    

DOI:10.1002/arch.940050105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMethotrexate‐resistant mosquito (Aedes albopictus) cell mutants were used as starting material for the purification of dihydrofolate reductase. Initial fractionation of a crude cell lysate by ammonium sulfate precipitation showed an enrichment of enzyme activity in the 60‐100% pellet. Purification of this ammonium sulfate fraction on a Sephadex G‐75 column prior to affinity chromatography was required for maximal yield of purified protein. A protein with dihydrofolate reductase activity and an Mrof 24,000 was eluted from a methotrexate‐agarose column with 0.5 M Tris‐HCl, pH 8.5, containing 2 mM folic acid. A 21‐fold increase in specific activity relative to that in the crude cell lysate was obtained, and amino acid sequence analysis confirmed that dihydrofolate reductase from the affinity column migrated as an electrophoretically pure band on SDS polyacrylamide gels. The initial 20 amino acid residues of the mosquito dihydrofolate reductase were identified by microsequencing and compared to those of murine, human, and bacterial dihydrofolate reductas

ISSN:0739-4462    

DOI:10.1002/arch.940050106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940050101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY