Biosynthesis membrane attachment mechanisms

Additional studies investigating nicotine and its biological effects are numerous a few examples will be listed here. The damage induced increase in alkaloid production in Nicotiana, and its mechanism have been investigated [44,45], Nicotine biosynthesis continues to be studied [46,47] and has included the use of NMR [48]. A synthesis of 1 from 3,3 -dipyridyl was reported [49]. Nicotine showed potential as a molluscicide [50], it was a potent inhibitor of TAK-induced activation of polymorphonuclear leukocytes [51], and it caused reduction of herpes simplex virus type 1 production, as well as reduction of viral attachment to cell membranes [52]. Mechanisms involved in the behavioral and cognitive effects of nicotine have been investigated [53]. 

The mechanism of toxicity for aminoglycosides has not been fully explained and is therefore unclear. It is known that the drug attaches to a bacterial cell wall and is drawn into the cell via channels made up of a protein, porin. Once inside the cell, the aminoglycoside attaches to the 30S bacterial ribosomes. Ribosomes are the intracellular structures responsible for manufacturing proteins. This attachment either inhibits protein biosynthesis or causes the cell to produce abnormal, ineffective proteins. The bacterial cell cannot survive with this impediment. This explanation, however, does not account for the potent bactericidal properties of these agents, since other antibiotics that inhibit the synthesis of proteins (such as tetracycline) are not bactericidal. Recent experimental studies show that the initial site of action is the outer bacterial membrane. The cationic antibiotic molecules create fissures in the outer cell membrane, resulting in leakage of intracellular contents and enhanced antibiotic uptake. This rapid action at the outer membrane probably accounts for most of the bactericidal activity. 

More recently, Baron and Abrams (1971) isolated a protein (nectin) from S. faecalis membranes, which is required for the attachment of ATPase to the membrane. It is a heat-labile protein of low molecular weight and it is believed that the combination of ATPase, nectin, and an ATPase receptor site on the membrane may represent the mechanism for membrane biosynthesis. 

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