Subunit structure of the phycobiliproteins of blue-green algae

The phycobiliproteins of the blue-green algae Synechococcus sp. and Aphanocapsu sp. were characterized with respect to homogeneity, isoelectric point, and subunit composition. Each of the biliproteins consisted of two different noncovalently associated subunits, with molecular weights of about 20,000 and 16,000 for phycocyanin, 17,500 and 15,500 for allophycocyanin, and 22,000 and 20,000 for phycoerythrin. Covalently bound chromophore was associated with each subunit.

Isolation of a basic protein antigen of low ragweed pollen

A fractionation method has been developed for the preparation of a basic protein antigen (BPA-R) from ragweed pollen. This antigen possesses potent allergenic activity. It is homogeneous by gel filtration on Sephadex G-100 and carboxymethyl-Sephadex chromatography. By the former technique the molecular weight of the BPA-R was estimated to be 28 000. Judged by its physicochemical and immunologic properties the BPA-R appears to be distinct from several other highly purified antigens currently isolated from ragweed pollen.The BPA-R and AgE (a highly purified acidic protein antigen) when tested together in Ouchterlony analysis displayed reactions of typical partial immunological identity with rabbit anti-ragweed sera which were produced by hyper immunization utilizing complete Freund's adjuvant. In contrast rabbit antisera, produced on a shorter schedule with BPA-R (using incomplete Freund's adjuvant), failed to react by Ouchterlony test with the AgE but reacted strongly with the BPA-R. Further immunological as well as chemical studies will be necessary to elucidate the antigenic relationship between these moieties.

On the relationship between ribulose diphosphate carboxylase and protochlorophyllide holochrome of Phaseolus vulgaris leaves

The relationship between ribulose diphosphate carboxylase (3-phospho-d-glycerate carboxy-lyase [dimerizing], EC 4.1.1.39, formerly known as carboxydismutase) and protochlorophyllide holochrome of etiolated Phaseolus vulgaris leaves has been studied.A procedure for partially selective extraction of the two proteins was devised using tris-HCl buffer first without and then with Triton X-100. Ribulose diphosphate carboxylase was readily extracted from etiolated bean leaves without Triton X-100, and protochlorophyllide holochrome was extracted on the addition of Triton X-100. Optimal extraction conditions for protochlorophyllide holochrome have been found to be different for tissues of different ages.

Isolation and spectral characterization of phycobiliproteins

Several phycobiliproteins were prepared chromatographically pure and their absorption, fluorescence-emission, fluorescence-excitation and fluorescence-excitation polarization spectra determined. Changes in these spectra with ionic strength of the aqueous medium and chromoprotein concentration were interpreted in terms of interchromophore energy transfer and protein subunit equilibria. The complexity of the polarization spectra confirms the presence of different types of chromophore, designated sensitizing (;s') and fluorescing (;f'), in a single protein.

Immunological distinction between fraction I protein and protochlorophyllide holochrome

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