Biomedical subjects

J Adamec

Publications and source records attributed to J Adamec.

At least 19 recordsLinked to original sources

PubMed1997

A cysteine endopeptidase isolated from castor bean endosperm microbodies processes the glyoxysomal malate dehydrogenase precursor protein.

A plant cysteine endopeptidase with a molecular mass of 35 kD was purified from microbodies of germinating castor bean (Ricinus communis) endosperm by virtue of its capacity to specifically process the glyoxysomal malate dehydrogenase precursor protein to the mature subunit in vitro. Processing of the glyoxysomal malate dehydrogenase precursor occurs sequentially in three steps, the first intermediate resulting from cleavage after arginine-13 within the presequence and the second from cleavage after arginine-33. The endopeptidase is unable to remove the presequences of prethiolases from rape (Brassica napus) glyoxysomes and rat peroxisomes at the expected cleavage site. Protein sequence analysis of N-terminal and internal peptides revealed high identity to the mature papain-type cysteine endopeptidases from cotyledons of germinating mung bean (Vigna mungo) and French bean (Phaseolus vulgaris) seeds. These endopeptidases are synthesized with an extended pre-/prosequence at the N terminus and have been considered to be processed in the endoplasmic reticulum and targeted to protein-storing vacuoles.

Amino Acid Sequence↗

PubMed1996

Mutational analysis of both subunits from rat mitochondrial processing peptidase.

Rat liver mitochondrial processing peptidase (MPP) is the primary peptidase that cleaves leader peptides from nuclearly encoded mitochondrial proteins following their transport from the cytosol to the mitochondrial matrix. This enzyme consists of two nonidentical subunits that have overall similarity to each other and share certain amino acid motifs. These include the putative metal-ion binding HFLEH motif in the beta-subunit and the HFLEK motif of the alpha-subunit, as well as a possibly helical amino acid stretch bearing a high concentration of negatively charged residues about 70 amino acids downstream of these motifs in both subunits. In order to achieve a better understanding of the role of certain amino acids in rat MPP, we performed site-directed mutagenesis on both of its subunits. Our results show that whereas both histidines and the glutamate of the HFLEH motif in the beta-subunit are crucial for MPP function, this holds true only for the glutamate in the related HFLEK motif in the alpha-subunit. In addition, functionally important negatively charged residues in the region 70 amino acids downstream occur only in the beta-subunit and not in the alpha-subunit. This indicates a functional asymmetry between the subunits, with the beta-subunit containing a majority of residues participating in the active center.

Amino Acid Sequence↗

PubMed1994

[Myocarditis mimicking myocardial infarct].

We describe 3 patients with an initial diagnosis of myocardial infarction, in whom a definitive diagnosis of myocarditis was subsequently established. All had precordial chest pain, electrocardiographic changes, elevated cardiac enzyme levels and regional wall motion abnormalities of the left ventricle compatible with myocardial infarction. During follow-up, all symptoms subsided and electrocardiographic tracings normalized. Regional wall motion abnormalities disappeared in two and persisted in one patient. These findings show that myocarditis may mimic myocardial infarction, and that the definitive diagnosis is generally established retrospectively.

Adult↗

PubMed1993

Heat shock applied early in sporulation affects heat resistance of Bacillus megaterium spores.

Cells of Bacillus megaterium 27 were challenged by a 30-min heat shock at 45 degrees C during various sporulation stages and then shifted back to a temperature permissive for sporulation (27 degrees C), at which they developed spores. Heat shock applied at 120 min after the end of the exponential phase induced synthesis of heat shock proteins (HSPs) in the sporangia and delayed the inactivation of spores at 85 degrees C. Several HSPs, mainly HSP 70, could be detected in the cytoplasm of these spores. An analogous HSP, the main HSP induced by increased temperature during growth, belongs to the GroEL group according to its N-terminal sequence. The identity of this protein was confirmed by Western blot (immunoblot) analysis with polyclonal antibodies against B. subtilis GroEL. Sporangia treated by heat shock immediately or 240 min after exponential phase also synthesized HSPs, but none of them could be detected in the spores in an appreciable amount. These spores showed only a slightly increased heat resistance.

Amino Acid Sequence↗

PubMed1988