Heat stability and activity levels of aspartate aminotransferase and alanine aminotransferase in British Littorinidae

Aspartate aminotransferase and alanine aminotransferase activity levels wer e determined in crude homogenates of Littorina arcana, Littorina littorea, Littorina compressa, Littorina neglecta, Littorina obtusata, Littorina faba lis, Melarhaphe neritoides and three forms of Littorina saxatilis; high sho re thin-shelled H, midshore thick-shelled M and barnacle dwelling B. In all the groups investigated, aspartate aminotransferase activity was higher th an alanine aminotransferase, and high shore species appeared to have higher activity levels of aspartate aminotransferase relative to alanine aminotra nsferase than did low shore species. Aspartate aminotransferase was more he at stable than alanine aminotransferase at 45 degrees C, and it was more he at stable in high shore than in low shore groups. Heat stability also varie d within a species; the enzymes of L. saxatilis H were more heat stable tha n those of L. saxatilis M from the same site. The enzymes of a small-barnac le dwelling form of L. saxatilis showed greater heat stability than sympatr ic samples of L. neglecta. The possible factors involved in these differenc es are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.