Non-identical Pairs Research Articles

Purification and properties of l-asparaginase from Serratia marcescens

Serratia marcescens asparaginase ( l-asparagine amidohydrolase, EC 3.5.1.1) has been purified 680-fold to apparent homogeneity as judged by sedimentation equilibrium ultracentrifugation, disc electrophoresis and immunodiffusion. The molecular weight by equilibrium sedimentation was found to be approx. 147 000. The results of sodium dodecylsulfate gel electrophoresis indicate that the enzyme is composed of four subunits of approximately identical molecular weight, and determination of N-terminal amino acids by dansylation suggests that these are present as two nonidentical pairs. The amino acid composition has been determined.

Multivariate Analysis in Twins

We present the results of a noncentral χ2 test applied to 63 like-sexed twin pairs.We have separated the pairs into two groups: 30 serologically identical and 33 serologically nonidentical pairs for nine sera of the blood groups ABO, MN, and Rh.The probabilities of monozygosity of the serologically identical pairs, calculated by the method of Maynard-Smith and Penrose, range from 0.83 to 0.92 — rather small values. With the help of Belgian frequencies of DZ and MZ twins, we could prove that there are about 50% chances of having less than two DZ pairs amongst the 30 serologically identicals.Consequently, our first group with 30 pairs is mostly MZ (less than 7 DZ pairs in 96% of the cases); while our second group, with 33 pairs, is completely DZ.We did not try to extract out of the 30 serologically identicals, such pairs that might “seem” DZ. For instance, we have kept in our first group two twins — one with blue and one with brown eyes — because the genetics of eye colour is not yet enough well-known to be safely used in twin-diagnosis; and also in memory of Madame de Sévigné, who had one brown and one blue eye. Imperfect as the composition of our sample is, we have avoided at least one mistake: adding, to surely DZ pairs, twins who are “seemingly” DZ, but not proven to be so.