Protein covalent attachment

Certain proteins are found to be covalently linked to lipid molecules. For many of these proteins, covalent attachment of lipid is required for association with a membrane. The lipid moieties can insert into the membrane bilayer, effectively anchoring their linked proteins to the membrane. Some proteins with covalently linked lipid normally behave as soluble proteins others are integral... 

Since the iron center of the protein was not shielding, the electron transfer occurred and cyclic voltammograms showed a voltanunogram with a redox couple with E1/2 at -390 mV. The eoverage obtained from the reduction peak area was 35 pmolcm, well correlated with the the value of 32 pmolcm" estimated from the AFM images. In summary, the SWCNT normal aligned can act as molecular wires to allow the electrical commrmication between the electrode and redox proteins covalently attached to the ends of SWCNTs. 

Addition of Mg to these complexes leads to their dissociation. However, addition of alkali leads to the appearance of cleaved DNA molecules having protein covalently attached to the DNA (see below). This enzyme also forms complexes with relaxed duplex DNA but these complexes are not dissociated by the addition of Mg and cleavage of the DNA is not found when alkali is added (Liu and Wang, 1979). Complexes between procaryotic topoisomerase I and DNA can also be detected by their retention on nitrocellulose filters. Using this method the preferential binding of the enzyme to an internal single-strand break in a linear duplex DNA has been shown (Dean et al., 1982 Dean and Cozzarelli, 1985). 

Bacteriophage 29 and the adenoviruses employ a completely different strategy (Figure 24.41b). They solve the problem by using a novel priming system that employs a protein covalently attached to the 5 -most nucleotide of each strand. In this case, there is no RNA that has to be removed because the terminal nucleotide that initiates the replication is a deoxyribonucleotide. 

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