Amino acids position-specific scores

The letters stand for specific amino acids and the identities of letters in certain positions are scored when we talk about levels of identity between two or more proteins. One then observes which positions (say 12, 13, and 17 in the B chain) have identical amino acids in all relaxin molecules. These are called preserved in the old model and that goes along with the assumption that all relaxins come from one ancestor gene and that all uncritical residues have changed due to mutational events.5... 

One significant difference between the LBT and the L-929 cytotoxicity test is the composition of the test median. The luminescent bacteria are suspended in a simple 2% sodium chloride solution, whereas the tissue culture cells require serum to supplemented their growth. Serum proteins and amino acids can complex with many chemicals, particularly metals, and thus rendo them unavailable to the test cells [27]. It was noted that for the 12 samples which were scored non-toxic with the LBT but positive to tissue culture, the Microtox F were <1.0 criteria established for a positive result. Depending upon the products or matoials under test, it may be practical and appropriate to use different F values as a failure point. These could correspond with the failure concentration established with the tissue culture or animal test for a specific class of material or product category. The highest sensitivity of the LBT should not be viewed as a cause of mme materials failing the test, but rather an q rtunity to set the failure point at a realistic and safe concentration. These correlations are discussed in depth by Jones [24]. 

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