Matrix metalloproteinases (MMPs) are zinc-containing endopeptidases. They degrade proteins by cleavage of peptide bonds. More than twenty MMPs have been identified and are separated into six groups based on their structure and substrate specificity (collagenases, gelatinases, membrane type [MT-MMP], stromelysins, matrilysins, and others).
Confidence votes 164. Alleles are the different forms of a gene. Alleles are corresponding pairs of genes located at specific positions in the chromosomes. Together, alleles determine the genotype. Alleles which determine some aspect of the phenotype, the physical appearance of an organism, are said to be coding alleles.
Genes and Alleles. Genes are pieces of DNA that code for traits expressed by the individual. There is more than one variant for many genes, slight differences in the copies of the gene that change the trait that the individual expresses. The variants of the gene are known as alleles and individuals who are diploid for that trait have two alleles, getting one copy of their genome from each parent.