Periodate-Oxidized Phosphomannan Y-2448: Structural Significance of Its Reaction With Alkali

Abstract

Informatioli regarding branching in this macromolecular polysaccliariclc derivative was not established. 'l'lie periodate-oxidatiori product i~eutralized dilute allcali rapidly a t p H 8.5-10.0, with climination of about :30yG of the phosphorus a s inorganic orthophosphate. :\bol~t 80'ji inorganic orthophosphate \\.as obtained b y longer treatment a t pI-I 10.1-10.5. Thcse observations arc shown to support t h e hypothesis t h a t diesterorthophosphatc groups (0.30 mole/molc mannosc u~~i t ) arc held betwecn carbon-6 of units othcr\\~ise linked only through carbon-1, and carbon-1 o l 60% of the carbon-2-1inl:ed units. After pcriodatc oxidation, botll phosphoester bontls m a y undergo p-alclehydo elimination by alkali; the unit having phosphatc in hemiacctal linlcagc ancl a mantiositlic attachment a T carbon-2 is presented as t h e more rcactivc site. Pcriotlnte oritlation also prorll~rcs sites for B-deallcosylation by allcali.'The esocellular polysacc1iaride derivative syntliesizecl by the yeast Ha?zsen~~la holskii NIiRL Y-2448 a i d isolated as the neutral potassium salt has tlie constituents D-mannose, phosphorus, and potassium in tlie ratio of 5 : 1 : 1 (1). This pliosplioiiiannan is sensitive to overoxidatioi~ by sodium inetaperiodate unless the reaction is conducted in tlie colc!; after neutralization of the formic acid liberated, the oxidized p r o d~~c t shows activit)~ with nlild al1;ali ~iiiusual for a polysacc1iaricle. we have souglit a n explanation for these behaviors i l l relation to the structure of phospliomaiinan Y-2448.I t is reasonable to consider overoxidation of this s~tbstailce possible since it seeins characteristic of yeast mannaiis to have a sigiiificailt proportion of their man~iose units (3lIU) 1inl;ed gl~~cosidically a t carbon-2 and/or cai-bon-3 (2-5). If in a reduciiig encl position, such units are 1;iiown to be susceptible to overoxiclation (3-5). Phosphate gro~lps in sugar phosphates (6) aiid in a polyril~ose phosphate (7) do not cause overoxiclation unless tlie position of the phosphate l.csults in formatio~i of a n active metlij7lc1~e group (6).There are indications in the literature, however, that the pl-esence of phosphate gi-oups might be involved ill the l~igli activity of periodate-oxidized phospliomannan with a1l;ali. Phosphates of p-aldeliydo alcoliols reaclily undergo phosphate elimination by mild alkali (8). Possibly closer pal-allels are pi-ovided by the smooth p-elimination, undei-mild alltalilie conditions, of tlie phosphate moiety from dialclehydes produced by periodate oxidation of substances such as ribonucleoside-5'-phosphate (9) and bj-the adaptation of this procedure to oligo-and poly-nucleotides (9, 10).Pi-eviously a fading e~icl poilit during alkaline titi-ation for formic acid in periodateoxidation solutions of carbohydrates usually has been associated with tlie presence of 0-foriiiyl esters derived from I-educing end groups (11-I.?), although other iiitei-pretations have been made (14, 15). 0-Formyl groups appear to be excluded as the source of "ester" acid...

A study of the phosphate linkages in phosphomannan in cell walls of Saccharomyces cerevisiae

“…The implications of this structure are extracellular phosphomannans, thus indicating the destruction of mannose 6-phosphate residues by periodate treatment. Jeanes & Watson (1962) concluded that these observations supportedthehypothesis that diester phosphate groups were held between C-6 of mannose units otherwise linked through C-1, and C-1 of mannose units which in turn had a mannosidic attachment at C-2. A structure was proposed in which the phosphate groups cross-linked oligosaccharide chains containing 1,2-and 1,3-linked mannose units.…”

“…The phosphomannan (0.1 %, w/v) was oxidized by sodium metaperiodate (7.4mM) buffered in 0.5Mammonium acetate buffer, pH 5 (I00ml), and in I00ml of unbuffered solution, in the dark at 4°C. These conditions limit over-oxidation (Jeanes & Watson, 1962). Periodate uptake was measured, on a portion (5 ml) from the buffered reaction, by the method of Malaprade (1928).…”

“…Evidence also suggested that phosphate occurred in diester linkage between C-6 of one mannose unit and the C-1 hemiacetal position of another. Jeanes & Watson (1962) have shown that phosphate diester linkages of this type do not yield PI when heated with alkali or on mild treatment with acid. However, the phosphate ester linkages are activated by periodate oxidation, which results in their being in ,B-aldehydo positions and liable to elimination by dilute alkali, giving Pi as the product.…”

The Chemistry of Polysaccharides of Fungi and Lichens

“…Patents have appeared for the production of phosphonomannans from Hansenula holstii (1 92, 193), Hansenula capsulata, Hansenula minuta, Pachyso fen tannophilus, Torulopsis pinus, and Saccharomyces pini ( 1 93). Sixty percent of 2-0-substituted D-mannopyranosyl residues are linked to structure 16 (195). The molecular weight is 16 X lo6, according to light-scattering measurements (194).…”

Some Contributions of Immunochemistry to Biochemistry and Biology

“…The immunological effect of the removal of two hydroxyl groups from mannose and their replacement by hydrogen was unknown (39). Nevertheless, the serological results gave the correct indication, since a prolonged purely chemical study of the Hansenula phosphomannan by Jeanes and her collaborators (40) showed that 33 per cent the linkages of mannose were between positions 1 and 2 and 47 per cent between positions 1 and 3. Similarly, we could predict from its reactions with antipncumococcal horse scra of Types II and VI (41), that the polysaccharide of Group A hemolytic streptococcus, the group so dangcrous for the human race, would contain at least a part of its high content of rhamnose bound in positions 1 and 3, as is the L-rhamnose in the capsular polysaccharides of these two pneumococcal types (42).…”