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Cysteine-containing peptides are produced by sequential clipping, but not released, from lupin 11S storage globulin during early germination

100%

Capraro J., Galanti E., Marengo M., Duranti M., Scarafoni A.

vol. 2

issue 1

The digestion of the seed storage proteins is a finely regulated process operated by several proteases whose action is influenced by the exposure of specific regions, which became progressively available upon their action. We focused our study on the initial stages of germination, where more subtle modifications to the storage proteins are expected. Small-size peptides containing cysteine residues and other possible metalbinding regions are de facto produced but are not released from the “parental” protein since they remain bound trough disulphide bridges. The meaning of these findings is discussed.

Purification and functional reconstitution of intact ral-binding GTPase activating protein, RLIP76, in artificial liposomes.

88%

Singhal S., Singhal J., Cheng J., Pikuła S., Sharma R., Zimniak P., Awasthi Y., Awasthi S.

2001

vol. 48

issue 2

551-562

We have recently shown that RLIP76, a ral-binding GTPase activating protein, mediates ATP-dependent transport of glutathione-conjugates (GS-E) and doxorubicin (DOX) (S. Awasthi et al., Biochemistry 39, 9327, 2000). Transport function of RLIP76 was found to be intact despite considerable proteolytic fragmentation in preparations used for those studies, suggesting either that the residual intact RLIP76 was responsible for transport activity, or that the transport activity could be reconstituted by fragments of RLIP76. If the former were true, intact RLIP76 would have a much higher specific activity for ATP-hydrolysis than the fragmented protein. We have addressed this question by comparing transport properties of recombinant RLIP76 and human erythrocyte membrane RLIP76 purified in buffers treated with either 100 or 500 μM serine protease inhibitor, PMSF. The purity and identity of recombinant and human erythrocyte RLIP76 was established by SDS/PAGE and Western-blot analysis. These studies confirmed the origin of the 38 kDa protein, previously referred to as DNP-SG ATPase, from RLIP76. Higher PMSF concentration resulted in lower yield of the 38 kDa band and higher yield of intact RLIP76 from both human and recombinant source. In contrast, the substrate-stimulated ATPase activity in presence of DNP-SG, doxorubicin, daunorubicin, or colchicine were unaffected by increased PMSF; similarly, ATP-dependent transport of doxorubicin in proteoliposomes reconstituted with RLIP76 was unaffected by higher PMSF. These results indicated that limited proteolysis by serine proteases does not abrogate the transport function of RLIP76. Comparison of transport kinetics for daunorubicin between recombinant vs human erythrocyte RLIP76 revealed higher specific activity of transport for tissue purified RLIP76, indicating that additional factors present in tissue purified RLIP76 can modulate its transport activity.

Modes of inhibition of cysteine proteases.

75%

Rzychon M., Chmiel D., Stec-Niemczyk J.

vol. 51

issue 4

861-873

Cysteine proteases are involved in many physiological processes and their hyperactivity may lead to severe diseases. Nature has developed various strategies to protect cells and whole organisms against undesired proteolysis. One of them is the control of proteolytic activity by inhibition. This paper presents the mechanisms underlying the action of proteinaceous inhibitors of cysteine proteinases and covers propeptides binding backwards relative to the substrate or distorting the protease catalytic centre similarly to serpins, the p35 protein binding covalently to the enzyme, and cystatins that are exosite binding inhibitors. The paper also discusses tyropins and chagasins that, although unrelated to cystatins, inhibit cysteine proteinases by a similar mechanism, as well as inhibitors of the apoptosis protein family that bind in a direction opposite to that of the substrate, similarly to profragments. Special attention is given to staphostatins, a novel family of inhibitors acting in an unusual manner.

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2 Acta Biochimica Polonica

1 Peptidomics

1 2016

1 2004

1 2001

1 Awasthi S.

1 Awasthi Y.

1 Capraro J.

1 Cheng J.

1 Chmiel D.

1 Duranti M.

1 Galanti E.

1 Marengo M.

1 Pikuła S.

1 Rzychon M.

1 Scarafoni A.

1 Sharma R.

1 Singhal J.

1 Singhal S.

1 Stec-Niemczyk J.

1 Zimniak P.

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Cysteine-containing peptides are produced by sequential clipping, but not released, from lupin 11S storage globulin during early germination

Purification and functional reconstitution of intact ral-binding GTPase activating protein, RLIP76, in artificial liposomes.

Modes of inhibition of cysteine proteases.