C. F. Phelps

The polyuronides: their molecular architecture☆

Abstract The polyuronides (uronic acid containing polymers) are considered for the first time as a coherent group. Until now the dearth of X-ray diffraction data resulted in many questions of polyuronide structure and conformation remaining unasked. The recent success in crystallizing the polyuronides is illustrated with X-ray diffraction patterns of hyaluronic acid, dermatan and chondroitin sulphates, heparan sulphate and heparin. The influence of the chemical structure, the glycosidic linkages and the charged substituents on the molecular conformations is considered together with the marked association with water which these molecules display. Computer-drawn projections of plausible molecular conformations are shown.

OBSERVATIONS ON AXINELLA SP. HEMAGGLUTININ

Nonantibody agglutinins and precipitins, called antibody-like substances by many workers, have been found in viruses, bacteria, sponges, mushrooms, plants, and invertebrates. Gold and Phelps have suggested the purely descriptive term Receptor Specific Proteins (RSP) to describe these substances, and have proposed a provisional classification scheme, based on their reactions in hemagglutination-inhibition (H/ I ) tests with various inhibitors. The marine sponge, Axinella sp., was found to contain a powerful soluble factor,2? 3 which precipitates a variety of substances, including purified B substance, and which agglutinates the red cells of a variety of species, from man down to lamprey. The reactions in H / I tests of Axinella sp. agglutinin 3 initially appeared to correspond to those of other lectins, that is, specific inhibition by simple sugars (&galactose and its amino derivatives), through binding of the inhibitor to the combining site of the agglutinin. While investigating the kinetics of hemagglutination (H) and precipitation for Axinella sp. and the properties of the purified aggl~tinin,~, however, certain anomalies were encountered : the agglutinin molecule is of low molecular weight (15-1 8,000) and probably has only one combining site, and D-galactose, the inhibitor in H/I tests, was shown to bind to the red cell surface.

Specificity of natural heterohaemagglutinins in snake venoms and other biological materials.

The ability of certain snake venoms to agglutinate red blood cells was observed as long ago as 1860 by MITCHELL [I] and experiments with them were reported by FLEXNER and NOGUCHI [2]. The specific interaction of antibodies with cell surface antigens on the red blood cell has been well documented. Less well known is the ability of a wide range of biological material to mimic this reaction, and for this reason they have been called antibody-like substances (AbLS) [3] or antibodymimetic substances [4]. Both antibodies against blood group substances and AbLS react in the haemagglutination reaction with sugar determinants on the antigen, though the recognitional specificity in mammalian antibodies is at the oligosaccharide level whereas most AbLS apparently react with single monosaccharide residues. Certain snake salivary secretions and sera contain heterohaemagglutinins [5]. Those in sera are antibodies. The primary question is: are the heterohaemagglutinins in snake salivary secretions antibodies or AbLS? To answer this question crude venom of Nuju naju (from Cambodia), Agkistrodon contortrix (US), from 4 species of Bothrops (Brazil) and Viperu puluestinae (Isreal) were used. The venoms of Nuju nuju, Agkistrodon contortrix and of the four Bothrops species have been chosen for our experiments because it is known from the pertinent literature that they contain haemagglutinins. Many other species of snakes do not contain haemagglutinins though in some cases closely related species can be distinguished and even intraspecies differences can be detected easily by serological tests.

Separation of haemagglutinins from haemolysins in extracts of the albumin gland of Helix aspersa.

Extracts of the albumin glands of Helix aspersa contain in addition to the anti‐A‐like haemagglutinin also a haemolysin. It was possible by chromatographic resolution to separate the haemolysin from the haemagglutinin. The haemolysin is unrelated to the ABO system as it reacts also with Oh (Bombay) red cells.