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The lactate dehydrogenase activity was examined in skeletal muscles of specimens of 53 species of Orthoptera belonging to five families of Ensifera and four of Caelifera. The results showed that: (1) the five families of Ensifera contain a low level of lactate dehydrogenase activity in their jumping muscles, whereas two families of Caelifera, Catantopidae and Acrididae, contain a far higher level; (2) in the four families of Caelifera, there are two well‐distinct levels of activity of lactate dehydrogenase in leg muscles, and (3) the lactate dehydrogenase activity in the jumping femurs is, in general, more than double that of the non‐jumping femurs. It was suggested that this difference in activity between specialized and non‐specialized leg segments represents a metabolic adaptation to burst muscular activity.

Lactate dehydrogenase has been analyzed electrophoretically, and its enzymatic activity level quantitatively evaluated in species of four Chilopoda orders. Scolopendromorpha, Scutigeromorpha, and most Lithobiomorpha showed a single activity band, while in Geophilomorpha more than one band was revealed, thus suggesting the existence of isozymes. Enzymatic activity was highest in Scutigeromorpha and in Scolopendromorpha, intermediate in Lithobiomorpha and very low in Geophilomorpha. It is presumed that the lactate dehydrogenase activity level has adaptive meaning in view of the different energy request during locomotion between slow and fast moving centipedes.

A4 (muscle-type) Lactate Dehydrogenase was purified to homogeneity from Dermochelys coriacea. The steady-state kinetic features of the enzyme show remarkable similarities with those displayed by many other heterothermal LDH's from cold-blooded vertebrates.

1. 1. Lactate dehydrogenase was purified to homogeneity from the chilopod Scolopendra cingulata. 2. 2. The enzyme has the usual molecular weight of approximately 150,000 and exists as a tetramer. It is l (+)lactate specific and some lines of evidence ascribe the molecule to the A-class (muscle-type of vertebrates). 3. 3. Surprisingly it displays Kcat values for both substrates pyruvate and lactate which are about two orders of magnitude lower than those known for other lactate dehydrogenases. 4. 4. Additionally, both Km for lactate and Kcat/Km for pyruvate are independent from assay temperature. 5. 5. The most striking feature of this enzyme, however, is its stability, as it still retains activity either after incubation at 90°C or in the presence of urea concentrations as high as 7.5 M.

1. 1. The A4 lactate dehydrogenase isozyme was purified to homogeneity from the tissues of Brook lamprey (Lampetra planeri) tench (Tenca tenca), smooth newt (Triturus vulgaris) and alpine newt (T. alpestris). 2. 2. These four species share their geographical distribution in the same freshwater habitats, often live together in the same station and two of them are congeneric. Steady-state kinetic investigations have shown that: 3. 3. Km (apparent) for pyruvate vs. temperature and (apparent) product Ki (Pyruvate) and Ki (Lactate) are fairly similar among species; 4. 4. kcat/Km decreases with temperature in the case of the newts but increases in the case of both lamprey and tench; 5. 5. Thermostability does not correlate to preferred ambient temperature and, in particular, tench LDH starts being inactivated up to 65°C. 6. 6. Thermostability does not correlate with activation energy either; 7. 7. No clear relationships can be demonstrated either between activation energy and conformational transitions in the molecule (these latter indicated by breaks in the Arrhenius plots) nor between activation energy and molecular flexibility, investigated by melting experiments.

1. The authors studied certain characteristics of the acetylcholinesterase present in Allolobophora caliginosa ; a good purification of the enzyme was achieved by homogenization, ultracentrifugation and then by Sephadex G-200 and DEAE-cellulose chromatographies. 2. Three enzymatic forms, probably monomeric, dimeric and tetrameric were isolated. The monomeric one is quantitatively prevailing and shows a higher specific activity; it seems to be composed of of two subunits with the same molecular weight. 3. The various active fractions are inhibited by eserine and hydrolyse acetylthiocholine more rapidly than butyrylthiocholine; besides, this latter does not cause substrate inhibition. 4. The enzyme is classifiable as acetylcholine hydrolase (E.C. 3.1.1.7).

1. 1. A purification of the enzyme from the starting material was achieved by means of butanol and acetone fractionations and, successively, by DEAE cellulose and Sephadex G-200 chromatographies. 2. 2. Two enzymatic forms were separated; they showed various similar characteristics but differed greatly in specific activity. 3. 3. It is probable that in A. caliginosa a sole alkaline phosphatase form exists and the less active fraction is partly denatured enzyme. 4. 4. It is not completely possible to exclude the existence of two isoenzymes.

1. 1. Like other lamprey species, Lampetra planeri displays LDH chains of a single type. Since lampreys are more related to vertebrates than myxines, which do have usual A and B monomers, we suspect that either a gene inactivation or a gene loss occurred in the former group. 2. 2. The characterization of the enzyme gave interesting results. From the standpoint of its affinity for ion exchangers, it behaves as if it is composed of A-type chains. 3. 3. From the standpoint of substrate and product inhibition, it resembles much more closely the B containing isozyme. 4. 4. Since literature reports that the other known single-chained LDH's from lampreys are definitely of the A type, we suggest the possibility that L. planeri enzyme underwent some orthologous evolution which brought it to resemble the heart isozyme.