Crystallization, preliminary X-ray analysis and amino acid sequence studies of an “external” functional unit from the Rapana thomasiana grosse (mollusc, gastropod) hemocyanin

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• 作者：Perbandt ; M. ; Chandra ; V. ; Idakieva ; K. ; Parvanova ; K. ; Rypniewski ; W. ; Stoeva ; S. ; Voelter ; W. ; et. al.
• 关键词：A1. Biocrystallization ; A1. Crystal structure ; A1. X-ray diffraction ; A2. Growth from vapor ; A2. Single crystal growth
• 刊名：Journal of Crystal Growth
• 出版年：2001
• 出版时间：November, 2001
• 年：2001
• 卷：232
• 期：1-4
• 页码：353-360
• 全文大小：424 K

文摘

Rapana thomasiana hemocyanin is a representative of molluscan (gastropodan) dioxygen-transporting proteins. The cylindrical hemocyanin aggregates are composed of two structural subunits, RHSS1 and RHSS2. The 420kDa subunit RHSS2 contains eight 50–55kDa functional units. Each unit has a single dioxygen-binding dinuclear copper-containing active site. Molluscan hemocyanin functional units can be subdivided into “internal units”, forming the so-called “arch” inside the hemocyanin cylinders, and “external” units, building the cylinder wall of the aggregates. The “external” oxygenated functional unit RtH2-e of the Rapana hemocyanin subunit RHSS2 was isolated and crystallized in two crystal forms. Type I crystals are small but X-ray suitable and show bipyramidal morphology. Preliminary data were collected to 3.3Å at 120K using synchrotron radiation. The space group is assigned to be the tetragonal P4₁2₁2 or its enantiomer with unit cell dimensions a=b=105.5Å and c=375.0Å. Type II crystals grow in thin plates and diffract to about 3.0Å. However, they are always twinned and cannot be utilized for data collection and structure analysis.