Polyfunctional proteins

Similarly, we could create a mutant in part of the polyfunctional protein and allow the synthetic substrate to be accepted by the functional parts and carried through to produce a completely different compound. The benefit of this type of manipulation is that synthetic procedures that are very difficult for chemists to do... 

Fatty acids are built from acetyl CoA as a starter and several molecules of malo-nyl CoA (D 3) by fatty acid synthase, as is shown schematically in Fig. 52. In yeast the enzymes involved are located on two polyfunctional proteins. It is still unclear whether similar polyfunctional enzymes exist in other organisms. 

Benzodiazepine Alkaloids and 4 Phenylquinolines (Figs. 154 and 155). The benzodiazepine alkaloids formed in moulds of the genus Penicillium are cyclic peptides formed from anthranilic acid and L-phenylalanine. The key intermediate cyclopeptine is probably synthesized by a polyfunctional protein resembling... 

Formation of the peptide part probably proceeds on a polyfunctional protein (A 3.1), Key intermediate may be a linear tripeptide bound covalently to the enzyme protein (Fig. 257). 

Stilbenes are formed by stilbene synthase, a polyfunctional protein (A 3.1) from one molecule of a cinnamoyl CoA derivative and three molecules of malonyl CoA... 

The flavane ring system is formed by the polyfunctional protein chalcone synthase from one molecule of a cinnamoyl CoA ester and 3 molecules malonyl CoA. The enzyme isolated from parsley (Petroselinum hortense) reacts with p-coumaroyl CoA and caffeoyl CoA as starter molecules (A 3.1). It uses the CoA esters as immediate substrates for the condensation reaction and contains neither an acyl carrier domain nor pantetheine. 

Several microbial peptides, e.g., gramicidin S, tyrocidine A, bacitracin and edeine A (Fig. 328), are formed on polyfunctional proteins (A 3.1). One to three... 

Identification of the functions of proteins and other polymeric complexes or cell proteomes, in which the achievements of proteomics contributes greatly, is the subject of intensive research [1], Modem technology now allows us to investigate not only individual protein molecules in living cell, but also to understand their interaction with other macromolecules and reveal their previously unknown functions. Several facts are determined participation of polyfunctional macromolecular protein complexes in the biosynthesis of fatty acids, involvement of erythrocyte membrane proteins macromolecular complexes in exchange of COJO, biological effects of some growth factors (polyfunctional proteins), which sometimes is achieved by interactions of other protein complexes, etc. [2-4],... 

Chloro-3,5-dinitrophenacyl bromide The compound has been used as a polyfunctional protein reagent and reacts with various functional groups. With tryptophan it forms a charge-transfer complex and reaction occurs with substitution of Cl or Br 110)... 

The modem era of biochemistry and molecular biology has been shaped not least by the isolation and characterization of individual molecules. Recently, however, more and more polyfunctional macromolecular complexes are being discovered, including nonrandomly codistributed membrane-bound proteins [41], These are made up of several individual proteins, which can assemble spontaneously, possibly in the presence of a lipid membrane or an element of the cytoskeleton [42] which are themselves supramolecular complexes. Some of these complexes, e.g. snail haemocyanin [4o], are merely assembled from a very large number of identical subunits vimses are much larger and more elaborate and we are still some way from understanding the processes controlling the assembly of the wonderfully intricate and beautiful stmctures responsible for the iridescent colours of butterflies and moths [44]. 

The steady structure determined by the value of Kw (Fig. 1) for the entire class of carboxylic CP obtained by precipitation copolymerization is one of the most important factors determining the possibility of reversible bonding of proteins absorbed by carboxylic CP with a high sorption capacity [16,19]. Thus, for the MA-HHTT system (Fig. 2), a complete desorption of enzyme is carried out on crosslinked copolymers characterized by low Kw values. In crosslinked structures exhibiting looser structure (Kw P 1), owing to the mobility of chain fragments of CP especially in the process of desorption, the macromolecules of sorbed protein are irreversibly captured as a result of a marked polyfunctional interaction. 

Since the mechanism of interaction between proteins polyfunctional with respect to ionogenic groups and CP is complex, an approximate method of calculation of sorption selectivity constants according to the inverse form of Langmuir isoterm should be used. Hence, the approximate values of AG, AH and AS obtained from Eq. (3.5) should be applied (Table 7). 

It was only around 1850 that the first amines were discovered by Wurtz [2], who considered them as alkylated (or arylated) derivatives of NH3. Nowadays, it is well known that the amine function is widespread among biologically important compounds, but mostly it is present in polyfunctional molecules such as amino acids, alkaloids, etc. Simple amines are very rare in nature, with the exception of tri-ethylamine and the trimethylammonium ion which come from the putrefaction of proteins. 

Thermoresponsive acrylamide co-polymers were also used to alter the physicochemical and biopharmaceutical properties of avidin. Similar to PEG, the acrylamide co-polymers with a lower critical solution temperature (LCST) of about 37 °C were conjugated to the protein amino groups. The polymers were conjugated either by polymer multipoint attachment using polyfunctional polymers or by single chain attachment using end-chain monoactivated polymer. In both cases, the polymer conjugation was found to produce bioactive derivatives with reversible thermal character (Fig. 11.12). 

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