Umecyanin

There are four other proteins - stellacyanin, rusticyanin, umecyanin and ami-cyanin (Table 3) which have been fairly extensively studied. A crystal structure determination for amicyanin from Thiobacillus versutus is now under way [61]. A number of other type 1 proteins have been identified. These include pseudo-... 

The type-1 blue copper proteins act as electron carriers azurin, plastocyanin, stellacyanin, umecyanin e.g. They are characterized by a rather strong LMCT (ligand to metal charge transfer) band near 600 nm and by small hyperline coupling constants A in EPR. Copper is bound to two imidazole groups of histidine and to two... 

Copper proteins are involved in a variety of biological functions, including electron transport, copper storage and many oxidase activities. A variety of reviews on this topic are available (Sykes, 1985 Chapman, 1991). Several copper proteins are easily identified by their beautiful blue colour and have been labelled blue copper proteins. The blue copper proteins can be divided into two classes, the oxidases (laccase, ascorbate oxidase, ceruloplasmin) and the electron carriers (plastocyanin, stellacyanin, umecyanin, etc.). 

The cucumber basic blue protein is made up of a single polypeptide chain of 96 amino acids containing a single copper ion with a molecular weight of 10000 (Adman, 1985). The amino acid sequence (Bergman et al., 1977) is very similar to those of stellacyanin and umecyanin. The copper in cucumber blue protein displays the characteristic spectroscopic properties of a typical blue copper site (Table 5-5). 

Unknown stellacyanin, umecyanin, cucumber basic blue copper protein... 

The blue copper proteins azurin, plastocyanin, stellacyanin, and umecyanin incorporate Cu bound to a combination of N/thiolate/thioether ligands. An important feature of these metalloenzymes is the facile copper(II)/(I) couple that these species exhibit, which is linked to the highly strained, asymmetric coordination geometry at the metal center. The synthesis of model complexes for these so-called Type 1 copper proteins has been reviewed. ... 

There is little information available regarding the function of stella-cyanin and umecyanin, which are isolated from nonphotosynthetic plant tissue. 

These have been quite extensive and results have been published for plastocyanin (51), azurin (52), stellacyanin (53), umecyanin (54), and rusticyanin (55) in both oxidation states. Fitting procedures are not sensitive to the inclusion of the Cu—S(Met) bond, and if the latter does contribute the best fit the bond distance obtained is not always reliable. In the case of azurin, the axial carbonyl group is not included in the fit. No information is obtained from EXAFS concerning bond angles. Table IV is a listing of data reported. It is noted that (average) Cu—N(His) bonds are persistently shorter than those obtained from... 

The 31P NMR spectra of nickel and zinc complexes of tetrakis(ethyl-phenylphosphinate)-substituted phthalocyanines showed the presence of several constitutional isomers.398 The formation of trimetallic (Ni2Pt) complexes by the reaction of nickel me.vo-tetratolylporphyrin derivatives with PtCl2-con-taining species has been shown by H and 13C NMR spectroscopy to be diastereoselective.399 The 111 NMR spectrum of nickel(II) umecyanin (a stellacyanin with an axial Glu ligand, demonstrates the unidentate coordination of Glu via the side-chain amode oxygen atom.400... 

The physiological functions of the phytocyanins are also currently unknown. This family of proteins consists of stellacyanin (20 kD) [97, 101], umecyanin (14 kD), the basic blue protein (from cucumber = plantacyanin) (8 kD), and cusacyanin (molecular masses see [17]). 

Fig. 37. Phylogenetic family tree of the four small blue protein families. The roots as well as the branching points to auracyanin, rusticyanin, halocyanin, and umecyanin are currently not known. Plastocyanin occurs in bacteria as well as in eukaryotes. Ascorbate oxidase was used as reference protein in creating the diagram. The plant allergen Ra3 is a non-copper protein. Halocyanin is currently the only known archaeate copper protein. Adapted from Ryden and Hunt 1993 [71]...

Stellacyanins are different from other phytocyanins and cupredoxins by the nature of the axial ligand coordinated to the copper the axial ligand is a conserved glutamine instead of methionine. They also exhibit lower reduction potentials (180-280 mV vs. NHE) than other cupredoxins, and undergo redox reactions with small inorganic complexes or at electrodes at unusually fast rates.The stellacyanin subfamily includes stellacyanins from lacquer tree Rhus Vernicifera and cucumber Cucumis sativus, mavicyanin from green zucchini, and umecyanin from horseradish root. 

B. Stellacyanin, Umecyanin, and Mung Bean Blue Protein... 

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