Protein catabolism in thymus nuclei

Furlan, Miha; Jericijo, Marija

doi:10.1016/0005-2795(67)90096-7

Cited by 75 publications

(7 citation statements)

References 24 publications

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“…Components initially denaturing at 70°, as well as smaller amounts of those with a transition at 75°, appeared to be destabilized so that they denatured at 55-65°after standing; at the same time, DNA became exposed in a thermally unprotected form. We ascribe these changes to autolysis of the chromatin by bound endogenous enzymes which in part may involve a protease described by Furlan and Jericijo (1967) and Bartley and Chalkley (1970). Similar changes have been observed with some preparations of liver chromatin stored for longer times in a frozen condition (-20°).…”

Section: Correlation Of Denaturation Profiles With Structure Insupporting

confidence: 76%

Structure studies on chromatin and nucleohistones. Thermal denaturation profiles recorded in the presence of urea

Ansevin¹,

Hnilica²,

Spelsberg³

et al. 1971

Biochemistry

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Section: Correlation Of Denaturation Profiles With Structure Insupporting

confidence: 76%

Structure studies on chromatin and nucleohistones. Thermal denaturation profiles recorded in the presence of urea

Ansevin¹,

Hnilica²,

Spelsberg³

et al. 1971

Biochemistry

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“…In that study a protease with an optimum pH of 4.0 -5.5 was able to function at this acidic pH when associated with nucleic acid [46]. Other studies also have shown that nuclei of calf thymus and rat liver contain similar acidic proteases [34,441. The optimal pH of this protease was 4.0-4.5 with BSA as substrate.…”

Section: Discussionmentioning

confidence: 99%

Purification and characterization of a protease from Xenopus embryos

Miyata¹,

Yoshida²,

Kihara³

1989

European Journal of Biochemistry

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A proteolytic enzyme was purified from Xenopus embryos. The purification procedure consisted of fractionation of an extract of embryos with acetone, gel filtration of Sephadex G-75 and chromatography on carboxymethyl-cellulose and hydroxylapatite. The preparation of enzyme appeared to be homogeneous as judged by electrophoresis in polyacrylamide gels. This protease had a molecular mass of 43 -44 kDa and was composed of two subunits with molecular masses of 30 kDa and 13 kDa. The optimal pH of the reaction catalysed by the protease was approximately 4.0. This proteolytic activity was inhibited by antipain, leupeptin and iodoacetic acid; it was not affected by phenylmethylsulfonyl fluoride and pepstatin; and it was enhanced by dithiothreitol. In the presence of RNA, the optimal pH was shifted from pH 4.0 to pH 4.5. The protease was activated by addition of total RNA from Xenopus embryos, by poly(rU) or poly(rG). In contrast, after addition of tRNA or poly(rC), no activation of the protease was observed.Nearly all proteins in animal cells are continuously degraded to their constituent amino acids and this process contributes in an important way to the control of the levels of many enzymes and functional factors [l -31. Despite the importance of this process, the exact identification of the proteolytic enzymes that catalyze the degradation of proteins in vivo remains obscure. Animal cells contain many different proteases and there are both lysosomal and non-lysosomal pathways of protein degradation [4-61. Two of the major types of pathways for the degradation of proteins are clearly distinguishable, but many features of both pathways are not well understood. In general, the lysosomal proteases are small (20 -40 kDa) and they are maximally active under acidic conditions.Recent studies have indicated that the degradation of many intracellular proteins also occurs in the cytoplasm [7, 81. Although the mechanism of selection of substrates for degradation in the cytoplasm have not yet been established, many non-lysosomal proteases have been purified and characterized. For example, ATP-dependent proteases, multicatalytic proteases, and Ca2 +-dependent proteases have been found in animal cells as non-lysosomal proteases [4 -61.It has been reported that proteases play an important role in embryonic development [9 -121. We reported previously that a protease inhibitor, antipain, inhibits the incorporation of [3H]uridine into RNA in Xenopus embryos [13] and that the level of the proteolytic activity which is sensitive to antipain increased by a factor of several thousand during development up to the tail-bud stage [14]. In this report, we describe the purification of the antipain-sensitive enzyme and some of its properties. MATERIALS AND METHODS Chemicals Preparation ojeggs and embryosXenopus embryos obtained after mating were dejellied and allowed to develop to the tail-bud stage at room temperature. The embryos were immersed in cold acetone and homogenized in a glass homogenizer. The homogenate was centrifuged at 3000 r...

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“…Tissues rich in cells with rapid turnover rates, such as thymus, have been shown to contain histone-hydrolysing proteinases [5][6][7][8]. Histone-hydrolysing proteina-se activity has also been described in rat liver chromatin [9][10][11], chicken erythrocytes [12], and various other rat tissues [13].…”

Section: Introductionmentioning

confidence: 99%

“…Histone-hydrolysing proteina-se activity has also been described in rat liver chromatin [9][10][11], chicken erythrocytes [12], and various other rat tissues [13]. Principally, two different kinds of enzyme activities have been demonstrated to hydrolyse histones; one is a neutral serine enzyme present in high-salt extracts [2,5,9] and the other has an acidic pH optimum [5]. In addition, enzymes which hydrolyse a specific type of histone, such as HI [6][7][8]11], H2A [7,8,13,14], H2B [6,13], H3 [6][7][8] and H4 [13], have been recognized, although biochemical characterization and identification of most of these proteinases have not been completed.…”

Section: Introductionmentioning

confidence: 99%

Hydrolysis of histones by proteinases

Harvima

Yabe

Fräki

et al. 1988

Biochemical Journal

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Hydrolysis of histones by proteinases from rat liver, skin and other sources was studied by using a rat thymus histone preparation as the substrate and polyacrylamide-gel electrophoresis and densitometric analysis as the methods to detect histone subtypes and their hydrolysis. The rat mast-cell proteinase I effectively hydrolysed histones except type H4. Thrombin hydrolysed effectively histones H1 and H2A, whereas plasmin hydrolysed all types of histones. Cathepsin D hydrolysed especially histone H2A. Cathepsins B and L hydrolysed all histones more slowly, and cathepsin H hydrolysed them extremely slowly. Epidermal aminoendopeptidase did not hydrolyse histones. Trypsin and chymotrypsin were used as reference enzymes, which hydrolysed all types of histones in very low concentrations. This study suggests that a variety of proteinases could play a role in histone hydrolysis. Hydrolysis of a specific subtype of histones, such as histone H2A at pH 6 by cathepsin D, may be directly involved in regulation of epidermal-cell differentiation.

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Protein catabolism in thymus nuclei

Cited by 75 publications

References 24 publications

Structure studies on chromatin and nucleohistones. Thermal denaturation profiles recorded in the presence of urea

Structure studies on chromatin and nucleohistones. Thermal denaturation profiles recorded in the presence of urea

Purification and characterization of a protease from Xenopus embryos

Hydrolysis of histones by proteinases

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