PHOTOCHEMISTRY OF PHYCOBILIPROTEINS: RECIPROCITY OF REVERSIBLE PHOTOCHEMISTRY AND AGGREGATION IN PHYCOERYTHROCYANIN FROM Mastigocladus laminosus
PHOTOCHEMISTRY OF PHYCOBILIPROTEINS: RECIPROCITY OF REVERSIBLE PHOTOCHEMISTRY AND AGGREGATION IN PHYCOERYTHROCYANIN FROM Mastigocladus laminosus
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DOI：
10.1111/j.1751-1097.1989.tb05573.x
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发表时间：
1989-06
影响因子：
3.3
通讯作者：
S. Siebzehnrübl;R. Fischer;W. Kufer;H. Scheer
中科院分区：
文献类型：
--
作者：
S. Siebzehnrübl;R. Fischer;W. Kufer;H. Scheer
摘要：(A)板蓝藻及其分离的α-亚基的天然PEC在α-84藻蓝胆素发色团的光谱区表现出光致变色反应，其最大差值分别为502和570 nm。(2)天然PEC及其β-亚基在6 0 0-6 2 0 nm范围内几乎没有可逆光化学，β-亚基上的藻蓝胆素发色团在该区域吸收最大；(3)在pH=7.0时或pH≤3时，天然PEC保留可逆光化学。在670 nm(pH≤3)附近出现不可逆的吸光度增加。(D)在4-5M尿素或1M硫氰酸钾存在下，可逆光反应差谱的幅度最大，这是已知的将藻胆蛋白聚集体解离成单体的条件。同时，藻蓝胆素发色团(S)不可逆漂白，(E)在高聚集体中，例如在藻胆体中，幅度变得非常小。(F)天然PEC的光转化导致其在三聚体和单体之间的聚集平衡发生可逆移动。(G)PEC的藻红素发色团参与了PEC的可逆光化学，聚集态不仅对聚集态有影响，而且发色团的状态对聚集态也有影响。这可以直接或间接地通过释放其他多肽、通过光动力效应等构成作为感官色素的假定功能中的主要信号。
Abstract— (a) Native PEC from the cyanobacterium, Mastigocladus laminosus, and its isolated α‐subunit show photoreversibly photochromic reactions with difference‐maxima around 502 and 570 nm in the spectral region of the α‐84 phycoviolobilin chromophore. (b) Native PEC and its β‐subunit show little if any reversible photochemistry in the 600–620 nm region, where the phycocyanobilin chromophores on the β‐subunit absorb maximally, (c) Reversible photochemistry is retained in ureadenatured PEC at pH = 7.0 or pH ≤ 3. The difference maxima are shifted to 510 and 600 nm, and the amplitudes are decreased. An irreversible absorbance increase occurs around 670 nm (pH ≤ 3). (d) The amplitude of the reversible photoreaction difference spectrum is maximum in the presence of 4–5 M urea or 1 M KSCN, conditions known to dissociate phycobiliprotein aggregates into monomers. At the same time, the phycocyanobilin chromophore(s) are bleached irreversibly, (e) The amplitude becomes very small in high aggregates, e.g. in phycobilisomes. (f) In a reciprocal manner, the phototransformation of native PEC leads to a reversible shift of its aggregation equilibrium between trimer and monomer. The latter is favored by orange, the former by green light, (g) It is concluded that the phycoviolobilin chromophore of PEC is responsible for reversible photochemistry in PEC, and that there is not only an influence of aggregation state on photochemistry, but also vice versa an effect of the status of the chromophore on aggregation state. This could constitute a primary signal in the putative function as sensory pigment, either directly, or indirectly via the release of other polypeptides, via photodynamic effects, or the like.