Two unrelated phosphoenolpyruvate carboxylase polypeptides physically interact in the high molecular mass isoforms of this enzyme in the unicellular green alga Selenastrum minutum.

In the chlorophyte Selenastrum minutum, phosphoenolpyruvate carboxylase (PEPC) exists as two kinetically distinct classes of isoforms sharing the same 102-kDa catalytic subunit (p102). Class 1 PEPC is homotetrameric, whereas Class 2 PEPCs consist of three large protein complexes. The different Class 2 PEPCs contain p102 and 130-, 73-, and 65-kDa polypeptides in different stoichiometric combinations. Immunoblot, immunoprecipitation, and chemical cross-linking studies indicated that p102 physically interacts with the 130-kDa polypeptide (p130) in Class 2 PEPCs. Immunological data and mass spectrometric and sequence analyses revealed that p102 and p130 are not closely related even if a p130 tryptic peptide had significant similarity to a conserved PEPC C-terminal domain from several sources. Evidence supporting the hypothesis that p130 has PEPC activity includes the following. (i) Specific activity expressed relative to the amount of p102 was lower in Class 1 than in Class 2 PEPCs; (ii) reductive pyridoxylation of both p102 and p130 was inhibited by magnesium-phosphoenolpyruvate; and (iii) biphasic phosphoenolpyruvate binding kinetics were observed with Class 2 PEPCs. These data support the view that unicellular green algae uniquely express, regulate, and assemble divergent PEPC polypeptides. This probably serves an adaptive purpose by poising these organisms for survival in different environments varying in nutrient content.

[Automatic regulation of sinus rhythm in patients with migraine]. / Automatyczna regulacja rytmu zatokowego serca u chorych z migrena.

The clinical symptoms of migraine point to autonomic disturbances, especially to disrupted regulation of the circulatory system and autonomic balance. Searching for more accurate autonomic system studies we turned to the spectral analysis of cardiac rhythm changes, that allows to estimate the autonomic balance in sinus node. 44 patients with migraine were studied and the results were compared with those obtained in 74 healthy subjects. The reduced influence of both sympathetic and parasympathetic part of autonomic system on the sinus rhythm in migraine patients was found. The autonomic balance is shifted to the parasympathetic innervation side in patients with migraine.

[Studies of heart rhythm variability in migraine. Preliminary communication]. / Badanie zmiennosci rytmu serca w migrenie. Doniesienie wstepne.

Spectral analysis of hart rhythm variability makes possible assessment of the state (power) of autonomic innervation of the heart. The reported study was carried out in 40 patients (22 women) with migraine. The studies were done in times between migraine attacks. The control group comprised 62 clinically healthy subjects. In most patients (over 61%) the sympathetic and parasympathetic innervation of the heart was weaker than in healthy subjects and the index of automatic equilibrium in the sinus node was lower than in controls.