Proteins insect

In the case of fumonisin control, there is also a strong relationship between insect damage and fusarium ear rot. Corn genotypes containing the anti-insectant protein Bt had lower fumonisin content (Munkvold et al., 1997, 1999). 

Over the last twenty years biophysical work on this preparation has concentrated mainly on the elucidation of the filament structure and cross-bridge conformations (Reedy et al., 1965 Squire et al., 1977 Wray, 1979 Clarke et al., 1986 Reedy et al., 1987), and on the mechanical characterisation of various equilibrium states and of the kinetics of the cross-bridge cycle (Jewell Ruegg, 1%6 White, 1970 Tregear, 1977 Gtith et al., 1981 White Thorson, 1983). The biochemistry of ATP hydrolysis by the insect proteins has received less attention than that of vertebrate muscle proteins, primarily because of shortage of tissue, but recently aspects of the biochemical kinetics have been investigated (White et al., 1986). 

Antifreeze proteins, that are 3-4 times as effective as those in fish, have been isolated from some insects and other arthropods.1 11 0 They help beetle larvae to overwinter. The insect proteins have a parallel P helix structure resembling that in Fig. 2-17 and stabilized by S — S bridges.0 Some plants also synthesize antifreeze proteins.11 1 One of these, isolated from carrots, is a member of the leucine-rich-repeat family ... 

Rothemund S., Liou Y. C., Davies P. L., Krause E. and Sonnichsen E D. (1999) A new class of hexahelical insect proteins revealed as putative carriers of small hydrophobic ligands. Structure Fold Des. 7, 1325-1332. 

Of fundamental significance to understanding transferrin structure and function is the two-fold internal amino acid sequence repeat. In each protein, the N-terminal half of the polypeptide is homologous with the C-terminal half, with the level of identity between the two halves ranging from 26-28% in the insect proteins to —40% in higher transferrins and as high as 46% in melanotransferrin. This repeat is expressed... 

The four metal-binding amino acid residues (2 Tyr, 1 Asp, 1 His) are present in both N- and C-sites of all transferrins so far sequenced, apart from melanotransferrin and the insect proteins (Table III). The same is true of the anion-binding Arg and Thr residues, and the residues at the N-terminus of the anion-binding helix are also strongly conserved. Superposition of the 81 common atoms of these residues, plus metal and anion, shows that their rms deviation in the N- and C-sites of diferric human lactoferrin is only 0.3 A. This close structural similarity is reflected in their spectroscopic properties. Where these have been compared, with the physiological Fe3+ and C032- ions bound, they are so similar as to be virtually identical (107, 56, 199). Nevertheless, there are a number of factors that can potentially lead to inequivalence in properties ... 

There are two cases that I felt most pleased about. One was the crystal structure analysis of an insect hemoglobin, in the late 1960s, when molecular evolution was not yet in evidence. It was a great surprise that an insect protein should have about the same structure as that of a mammalian protein. 

Recombinant baculoviruses and their lepidopteran insect cell hosts have become one of the most widely used expression systems for the production of recombinant proteins [49, 50]. Manipulation of the system is straightforward, and high yields of recombinant material can be readily obtained in a matter of a few weeks compared with the several months that are required with stable animal cell expression systems. Generally, the insect-produced proteins are intended for research applications rather than as pharmaceuticals. The glycans on insect proteins differ significantly from those found on animal cell proteins, and this has limited the development of an attractive expression system for production of human therapeutics. 

Similar to the animal cell pathway, fucose addition takes place after the action of A-acetylglucosaminyltransferase I, along with the continued processing of the mannose residues by a-mannosidase II (Figure 5). Both a-1,6 and a-1,3 linked fucose residues have been identified on insect proteins [54, 55]. 

One of the explanations for the toxic properties of some nonprotein amino acids is their ability to form anomalous proteins. When the structure of a particular compound is structurally analogous to its protein constituent, the nonprotein amino acid may be incorporated. The well-known case of canavanine substitution for arginine in insect proteins is due to the inability of most insects arginyl-tRNA synthetases to discriminate the two compounds (20). When canavanine containing food is consumed, proteins with disrupted tertiary structure are built and the insects may not survive. 

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