Cephalopod Hemocyanins: Structure and Function

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The study focuses on the structure and physiological function of hemocyanins, which are oxygen-carrying proteins found in the blood of some invertebrates. The amino acid sequence, and part of the 3-dimensional structure of one of these giant molecules (that from Octopus) has recently been determined by the investigator and her collaborators. The new work proposed will first examine the structure of a part of the gene for the Octopus hemocyanin, and then attempt to develop a system to express a portion of this gene in bacteria or other cells. This should ultimately allow directed mutation, to analyze the effects of particular amino acids on the oxygen binding function. The protein also contains attached carbohydrate groups; the composition and structure of representative ones will be determined, and their possible roles in determining protein structure and/or function examined. Finally, the program will focus on how portions of these giant molecules communicate with one another to regulate the cooperative binding of oxygen on many sites. This phenomenon of allosteric regulation is common to many other important proteins, and is still not completely understood.Hemocyanins are oxygen transport proteins found exclusively in molluscs and arthropods. The octopus hemocyanins are truly enormous molecules, with molecular weights in the millions. As a result of recent breakthroughs in structure and sequence analysis of these molecules, the investigators are poised to interpret the evolution and function of hemocyanin at a level of sophistication never before possible.