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E Konieczna

Publications and source records attributed to E Konieczna.

7 recordsLinked to original sources
PubMed2001

The influence of supplemental components in nutrient medium on chitosan formation by the fungus Absidia orchidis.

Chitosan, a derivative of chitin, is a natural component of some fungus cell walls. It is formed by the complex action of chitin synthase and chitin deacetylase. The in vitro activity of these two enzymes is known to be influenced by several factors. We investigated the influence of ferrous ions, manganese ions, cobalt ions, trypsin, and chitin, as individual supplements to the nutrient medium, on the in vivo activity of chitin synthase and chitin deacetylase to form chitosan in the fungus Absidia orchidis. Manganese and ferrous ions gave the most significant results. These ions increase chitosan yields through an increase in biomass production rather than an increase of chitosan content in cell walls. Manganese and ferrous ions lowered the activity of chitin deacetylase; however, their influence on the activity of chitin synthase was more complex. The effects of trypsin and chitin on biomass and cell wall chitosan content were negligible, while cobalt ions completely inhibited the growth of fungi.

Absidia↗
PubMed2000

Analogues of arginine vasopressin modified in position 2 or 3 with naphthylalanine: selective antagonists of oxytocin in-vitro.

In this study we describe the synthesis and some pharmacological properties of six new analogues of arginine vasopressin (AVP). Five of the peptides were substituted in position 2 with L-1-naphthylalanine (L-1-Nal) or D-1-naphthylalanine (D-1-Nal); one had D-1-Nal in position 3. All analogues were tested in bioassays for pressor and antidiuretic activity. We also tested the uterotonic activity of the peptides in-vitro. Two of the new peptides were moderately potent V1a and oxytocin antagonists. The modifications proposed resulted in a drop or the removal of antidiuretic activity and in the removal of pressor activity, or conversion into moderate antagonists. Two peptides ([Mpa1, (L-1-Nal)2]AVP and [Mpal, (D-1-Nal)2]AVP) which appear not to interact with V1a and V2 receptors were exceptionally selective oxytocin antagonists in vitro. These compounds with selective oxytocin antagonistic activity may be promising candidates for the development of potential tocolytic agents for the prevention of pre-term labour.

Animals↗
PubMed1996

Surprising pharmacological activity of analogues designed by substitution of position 3 in arginine vasopressin (AVP) and 8-D-arginine vasopressin with L-2-napthylalanine.

In an attempt to develop more active and selective analogues of arginine vasopressin (AVP), two peptides have been designed, synthesized and tested for vasopressor (V1-receptors) and antidiuretic (V2-receptors) activities. We also estimated the uterotonic and anti-uterotonic activities of these compounds in-vitro. The first peptide, [(L-2-Nal)3] AVP is a highly active V2-agonist. The second analogue, [(L-2-Nal)3, (D-Arg)R]VP is among the most potent antagonists of the vasopressor response to AVP. Moreover, it is the first V1-antagonist devoid of anti-uterotonic activity. High antipressor potency of the second peptide was achieved without modification of position 1.

Animals↗
PubMedDate not supplied

Synthesis and some pharmacological properties of new V1/V2 antagonists of arginine-vasopressin with structural changes at their N-terminals.

In an effort to develop more effective and selective V2-antagonists of arginine-vasopressin (AVP) we designed and synthesized four new analogs of this hormone. The peptides were designed in order to explore how the combination of modification of thioacids occupying position 1 and substitutions of positions 2 and 4 by D-Phe and Ile respectively, will influence their antagonistic properties. Three of the reported analogs are moderately potent V1/V2 antagonists.

Amino Acid Sequence↗