A Transient Stimulation of Net Photosynthesis of Rye Leaves by {alpha}-Hydroxy-2-pyridinemethanesulphonic Acid ({alpha}-HPMS) due to Inhibition of Photorespiratory CO2 Release

The effects of -hydroxy-2-pyridinemethanesulphonic acid (-HPMS)upon net photosynthesis (P_n, the CO₂ compensation point (),post-lower illumination burst of CO₂ (PLIB) and post-lower temperatureburst of CO₂ (PLTB) in detached rye (Secale cereale L.) leaveswere investigated. At low concentrations ( 0.5 mol m^–3),-HPMS initially stimulated P_n and decreased the magnitude ofboth PLIB and PLTB. The decreased at all concentrations of-HPMS (0.05–5.0 mol m^–3. The effects of -HPMS onP_n and were time-dependent and, after a few minutes, the P_nwas inhibited while values increased considerably. At a higherconcentration (5.0 mol m ^–3), the transient effects of-HPMS were shorter () or not observed at all (P_n. Both PLIBand PLTB, when expressed in relation to P_n, increased at higherlevels of this compound. Similar data with respect to the effectsof -HPMS on PLIB and PLTB were found for leaves of dandelion(Taraxacum officinale L.). The results suggest that -HPMS may stimulate P_n by inhibitingphotorespiration, as originally suggested by Zelitch (1966),but only at low concentrations and over a short time span. Thedecrease of PLIB and PLTB values at low -HPMS levels is consistentwith these processes being a residual activity of the glycolatepathway. Key words: CO₂ compensation point, -hydroxy-2-pyridinemethanesulphonic acid, photorespiration, photosynthesis     

An NTP-Binding Protein That Cross with a Ras-Specific Antibody in the Myceia of Neurospora crassa

A Ras-related NTP-binding protein was partially purified froma membrane fraction derived from the mycelia of Neurospora crassa.[-³²P]ATP and [-³²P]GTP were incubated with mem brane and solublefractions which were then irradiated with UV light to inducecrosslinking of tightly bound nucleotides. After SDS-polyacrylamidegel electrophoresis, blotting onto a nitrocellulose filter andautoradiography it was apparent that most of the proteins thatbound [-³²P]-GTP also bound [-³²P]ATP. Pretreatment of the membranefraction with Ras-specific antibody effectively blocked thebinding of [-³²P]ATP and [-³²P]GTP to several ATP-GTP-bindingproteins. The band of a protein with a molecular weight of 26kDa on the SDS-polyacrylamide gel cross-reacted strongly withthe Ras-specific antibody. The protein was extracted from thegel and further purified by repeated gel electrophoresis. Thepurified protein bound [-³²P]ATP, [-³²P]-GTP, [-³²P]CTP and[-³²P]UTP at 1.6x10^– M and was autophosphorylated in thepresence of [-³²P]ATP and [-³²P]GTP at 1.7x10 M. Pretreatmentof the protein with Ras-specific antibody partially blockedthe autophosphorylation in the presence of these nucleotides.The binding of [-³²P]ATP to the NTP-binding protein was blockedby addition of ATP at 10^–4–10^–3 M. ATP ata concentration of 10^–4 M prevented the binding of [-³²P]to a greater extent than did GTP at the same concentration.Binding of [-³²P]CTP and [-³²P]UTP to the protein was also observed. (Received October 7, 1991; Accepted July 14, 1992)     

Mycobacterial arabinan biosynthesis: the use of synthetic arabinoside acceptors in the development of an arabinosyl transfer assay

Information on the biosynthesis of the D-arabinans of the cellwall of Mycobacterium tuberculosis is rapidly emerging, withthe promise of new targets for drug development against tuberculosis.Accordingly, arabinosyl transferase assays were developed utilizingsynthesized [1–¹⁴C]-β-D-arabinofuranosyl-1-monophosphoryldecaprenolas donor and a variety of O- and S-alkyl arabinosides as acceptors.These were: -D-Araf-(15)--D-Araf-O- and -S-alkyl di-arabinosidesand -D-Araf-(15)--D-Araf-(15)--D-Araf-O- and -S-alkyl triarabinosides.Whereas the O- and S-alkyl monosaccharide acceptors were inactive,the O- and S-alkyl disaccharide and the O- and S-alkyl trisaccharideacceptors (<C12) possessed considerable acceptor activity,and the trisaccharide acceptors were more potent than the correspondingdisaccharides. The O-alkyl disaccharide acceptors with a C8alkyl chain were more active than those containing the C6 orC10 analogs. Chemical analysis of the enzymatically synthesizedproducts of the reactions demonstrated that β-D-arabinofuranosyl-1-monophosphoryldecaprenolwas an effective donor for two of the three potential arabinosyltransferases: β-D-arabinofuranosyl-1-monophosphoryldecaprenol:arabinan (15) arabinosyl transferase and β-D-arabinofuranosyl-1-monophosphoryl-decaprenol:arabinan β(12) arabinosyl transferase. The β(12) arabinosyltransferase activity was more in evidence in the presence ofthe O-alkyl disaccharide acceptor, whereas both transferaseswere about equivalent in the presence of the S-alkyl trisaccharideacceptor. The tuberculosis drug, ethambutol, a known mycobacterialarabinosyl transferase inhibitor, was inactive within thesearabinosyl transferase/acceptor based assay systems, supportingother evidence that a third activity, responsible for the formationof 13 linkage, is the drug target. acceptor arabinan biosynthesis glycosyltrans-ferase assay mycobacteria     

srb: a Bacillus subtilis Gene Encoding a Homologue of the {alpha}-Subunit of the Mammalian Signal Recognition Particle Receptor

We cloned a Bacillus subtilis gene (srb) encoding a homologueof the mammalian signal recognition particle receptor -subunit(SR). The gene is 987 bp in length and encodes a 329-amino acidprotein. The deduced amino acid sequence of the protein shared26.6, 36.2 and 49.7% identity with those of mammalian SR, archaebacterialDP and Escherichia coli FtsY, respectively. The protein containsthree conserved GTP-binding elements like the other three SRPreceptor proteins, though the N-terminal portion of the putativeB. subtilis protein was shorter than the others. Secondary structureprediction showed that an amphipathic -helix is positioned inthe N-terminal region. A defect in srb inhibited cell growthand protein translocation.     

Identification and characterization of an {alpha}-mannosidase from Trypanosoma cruzi

In this report we describe the first purification and characterizationof the acid -mannosidase from the human parasite Trypanosomacruzi. The purified enzyme exhibited a native mol. wt of 240000 Da and is apparently composed of four identical subunitsof mol. wt 58 000 Da. Each of the four subunits contains oneN-linked high-mannose-type oligosaccharide. The -mannosidaseexhibited a pH optimum of 3.5 and a pI of 5.9. This low pH optimumand the ability of swainsonine to inhibit its activity suggestthat the -mannosidase is a lysosomal enzyme. Antibodies againstthe T.cruzi enzyme did not react with mammalian lysosomal -mannosidaseand, conversely, antibody against a rat lysosomal -mannosidasedid not react with the T.cruzi enzyme. Thus, the T.cruzi enzymeappears to be distinct from its mammalian counterpart. -mannosidase lysosomal enzyme Trypanosoma cruzi     

Regulation of Drosophila Visual System Development by Nitric Oxide and Cyclic GMP

Photoreceptors undergoing target selection in the optic lobeof Drosophila express a nitric oxide sensitive soluble guanylatecyclase (sGC). At the same time, cells in the target regionof the optic lobe express nitric oxide synthase (NOS). Pharmacologicalinhibition of NOS, NO or sGC leads to disruption of the retinalprojection pattern in vitro, and the extension of individualretinal axons beyond their appropriate targets. The disruptiveeffects of NOS inhibition in vitro are prevented by adding acGMP analog. Mutations in the sGC alpha subunit gene, Gc1, reducesGC expression and attenuate NO-sensitive retinal cGMP productionin the visual system. Although the retinal projection patternis undisturbed in Gc1 mutants, they lack positive phototaxisas adults, suggesting inappropriate connections exist betweenthe photoreceptors and optic lobe interneurons in these flies.Preliminary results show that heat-shock expression of wild-typeGc1 during metamorphosis can restore positive phototaxis insevere Gc1 mutants. These in vivo results support the in vitrofindings that NOS and sGC activity are required to promote theappropriate retinal innervation of the optic lobe.     

A novel alpha1,2-fucosyltransferase (CE2FT-2) in Caenorhabditis elegans generates H-type 3 glycan structures

The 1,2-fucosyltransferase family (1,2FT) is the largest familyof glycosyltransferases in the genome of the free-living nematodeCaenorhabditis elegans, and early evidence suggests that eachmember may have a unique activity. Here we describe a C. elegansgene (designated CE2FT-2) encoding an 1,2FT that has the potentialto generate the sequence Fuc1-2Galβ1-3GalNAc-R, which isthe H-type 3 blood group structure. The CE2FT-2 cDNA encodesa putative transmembrane protein that shows 42% amino acid identityto a previously cloned C. elegans 1,2FT (termed CE2FT-1), buthas a very low identity (16–20%) to 1,2FT sequences inhumans, rabbits, and mice. A recombinant form of CE2FT-2 expressedin human 293T cells has a high 1,2FT activity toward Galβ1-3GalNAc-O-pNP,but unexpectedly, the enzyme is inactive toward the acceptorGalβ-O-phenyl. Thus, CE2FT-2 differs from all other 1,2FTspreviously described from animals that all utilize Galβ-O-phenyl.CE2FT-2 is expressed at all stages of worm development, butremarkably, promoter analysis of the CE2FT-2 gene using greenfluorescent protein reporter constructs indicates that the CE2FT-2is expressed exclusively in pharyngeal cells of the worm fromembryo to an adult stage. Because pharyngeal cells are knownto secrete their glycoconjugates to the nematode surface, theseresults may indicate that products of CE2FT-2 contribute tointeractions of the nematode with its environment or are usedas ligands for bacterial attachment. These findings, along withthose on other 1,2FTs in C. elegans, suggest that each 1,2FTin this organism may have a unique acceptor specificity, expressionpattern, and biological function.     

Molecular dynamics simulations of high-mannose oligosaccharides

Conformations of several high-mannose-type oligosaccharidesthat are generated during the biosynthetic degradation of Man₉GlcNAc₂to Man₅GlcNAc₂ have been studied by molecular dynamics (MD).Simulations were performed on NCI-FCRDC's Cray Y-MP 8D/8128supercomputer using Biosym's CVFF force field for 1000 Ps withdifferent initial conformations. The conformations of the two1,3- and the two 1,6-linkages in each oligomannose were different,suggesting that deriving oligosaccharide conformations basedon the conformational preferences of the constituent disaccharidefragments will not always yield correct results. Unlike otheroligomannoses, Man₉GlcNAc₂ appears to take more than one distinctconformation around the core 1,6-linkage. These various conformationsmay play an important role in determining the processing pathways.Using the data on the preferred conformations of these oligomannosesand the available experimental results, possible pathways forprocessing Man₉GlcNAc₂ to Man₅GlcNAc₂ by 1,2-linkage-specificmannosidases have been proposed. Conformational analysis ofMan₅GlcNAc₂ indicates that the addition of ß1,2-GlcNActo the 1,3-linked core mannose, besides serving as a prerequisitefor mannosidase II action as suggested earlier, may also preventthe removal of 1,3-mannose. The MD simulations also suggestthat the processing of the precursor oligosaccharide duringAsn-linked complex and hybrid glycan biosynthesis proceeds ina well-defined pathway involving more than one 1,2-linkage-specificmannosidase. Knowledge of the conformation of the processingintermediates obtained from the present study can be used todesign highly specific substrate analogues to inhibit a particularmannosidase, thereby blocking one processing pathway withoutinterfering with the others. carbohydrates conformation glycosidase inhibitors mannosidase oligosaccharide processing     

Uptake and Accumulation of {alpha}-Naphthalene Acetic Acid by Cell Suspensions of Galium mollugo L.

Fidgeon, C. and Wilson, G. 1988. Uptake and accumulation ofa-naphthalene acetic acid by cell suspensions of Galium mollugoL.—J. exp. Bot. 39: 241-249. Galium mollugo cell suspensions require -NAA for continued growthand cell division. The kinetics of -NAA uptake from the medium(B₅) by Galium cells was assessed using 1-¹⁴C -NAA in a standardratio of cells to medium (0.25 g: 2.5 cm³). It was found thatthe uptake of -NAA was rapid, over 90% being taken up within4 h. Cells which had accumulated -NAA for 4 h or more did notrelease it back into the medium. It was found that Galium cellsaccumulated -NAA against a significant concentration gradient;suggesting the participation of an active component in the uptakemechanism. The effect of free-space and surface adsorption onthe uptake of -NAA was determined by means of a repeated washtechnique. These two factors were found to be of importanceonly during the first hour of uptake. Neither dead cells norplasmolysed cells absorbed -NAA. It is clear that, in the normal growth cycle, Galium cells cantake up the available -NAA within 3 or 4 h of inoculation andthat this can stimulate a cell division response of 3-4 generationsover the subsequent 14 d. Key words: Galium, cell suspension, -naphthalene acetic acid     

Differential distribution of ERalpha and ERbeta mRNA in intrauterine tissues of the pregnant rhesus monkey

Twoestrogen receptor (ER) isoforms, ER and ER, have been described.However, no information is available in any species regarding thecomparison of ER and ER levels in pregnant intrauterine tissues.We investigated 1) distribution of ER and ER mRNA in myometrium, amnion, choriodecidua, and placenta; 2) theirabundance in intrauterine tissues at term not in labor (NIL) and inspontaneous term labor (STL); and 3) immunolocalization ofER and ER in pregnant rhesus monkey myometrium. Myometrium,amnion, choriodecidua, and placenta were obtained at cesarean sectionfrom monkeys in STL at 156-166 days gestational age(GA) (n = 4) and from control monkeys NIL at140-152 days GA (n = 4). RT-PCR was conducted to determineER and ER and glyceraldehyde-3-phosphate dehydrogenase mRNAabundance in four intrauterine tissues of the pregnant rhesus monkey.The cloned ER PCR fragment was subjected to sequence analysis. ERand ER were localized in the myometrium by immunohistochemistry. Wedemonstrated that 1) rhesus monkey ER shares >97%identity with human ER in the region sequenced; 2) both ERswere expressed in myometrium, amnion, and choriodecidua but not inplacenta in the current study; 3) ER and ER weredifferentially distributed in myometrium and amnion; 4) ERand ER were immunolocalized in myometrial smooth cells and smoothmuscle and endothelial cells of the myometrial blood vessels. Thebiological significance of these quantitative differences in ERsubtypes merits further study.

     

Effect of TNF-alpha on SMIT mRNA levels and myo-inositol accumulation in cultured endothelial cells

Previously we have shown that hyperosmolarity increasesNa⁺-myo-inositolcotransporter (SMIT) activity and mRNA levels in cultured endothelialcells. Because hyperosmolarity and cytokines, such as tumor necrosisfactor- (TNF-), activate similar signal transduction pathways, weexamined the effect of TNF- on SMIT mRNA levels andmyo-inositol accumulation. In contrastto the effect of hyperosmolarity, TNF- caused a time- andconcentration-dependent decrease in SMIT mRNA levels andmyo-inositol accumulation. The effectof TNF- on myo-inositolaccumulation was found in large-vessel endothelial cells (derived fromthe aorta and pulmonary artery) and cerebral microvessel endothelialcells. In bovine aorta and bovine pulmonary artery endothelial cells,TNF- activated nuclear factor (NF)-B. TNF- also increasedceramide levels, and C₂-ceramidemimicked the effect of TNF- on SMIT mRNA levels andmyo-inositol accumulation in bovineaorta endothelial cells. Pyrrolidinedithiocarbamate, genistein, and7-amino-1-chloro-3-tosylamido-2-hepatanone, compounds that can inhibitNF-B activation, partially prevented the TNF--induced decrease inmyo-inositol accumulation. The effectof TNF- on myo-inositolaccumulation was also partially prevented by the protein kinase Cinhibitor calphostin C but not by staurosporine. These studiesdemonstrate that TNF- causes a decrease in SMIT mRNA levels andmyo-inositol accumulation in culturedendothelial cells, which may be related to the activation of NF-B.

     

Xyloglucan and r{beta}-D-Glucan in Cell Walls of Rice Seedlings

Cell walls of 4-day old rice seedlings were extracted successivelywith ammonium oxalate-oxalic acid, 4% KOH and 24% KOH. A rß-D-glucanpreparation and a xyloglucan preparation were isolated fromthe 4% KOH extract and 24% KOH extract, respectively. Methylationanalysis and enzymic degradation studies of the polysaccharidesshowed that the former was built up predominantly of repeating-oligosaccharideunits of 3-O-rß-cellobiosyl-D-glucose and 3-O-rß-cellotriosyl-D-glucosein a molar ratio of 2.6 : 1.0, and the latter was of repeating-oligosaccharideunits of -D-xylosyl-(16)-rß-D-glucosyl-(14)-[-D-xylosyl-(16)]-rß-D-glucosyl-(14)-D-glucose,-D-xylosyl-(16)-rß-D-glucosyl-(14)-D-glucose and cellobiose. ¹ Present address: Department of Botany, Iowa State University,Ames, Iowa 50011, U.S.A. (Received August 29, 1981; Accepted January 12, 1982)     

Sialylation of n-alkyllactosides, galactosides and glucosides by sialyltransferases from rat liver Golgi vesicles

nAlkyl - and -lactosides, galactosides and glucosides with differentalkyl chain lengths (C₂, C₈, C₁₄, and C₂₀) were synthesizedand used as acceptors for sialyltransferases from rat liverGolgi vesicles. The -galactosides, -glucosides, and both - and-lactosides, were sialylated. Keeping the acceptor concentrationconstant, sialylation rates reached a maximum for the n-octyl- and -lactosides, n-Octyl -galactoside and noctyl -glucoside,respectively. noctyl -glucoside, respectivwly. n-Octyl -galactosideand n-octyl -glucoside were not sialylated. The reaction productswere characterized by TLC. With n-octyl lactoside and galactosideas acceptors, two major sialylation products were formed. Thjeycould be separated by preparative TLC, and their structureswere identified as 2–3 and 2–6 sialylated acceptors,respectively, by a combination of periodated oxidation, NaBD₄reduction,permethylation and subsequent analysis by fast atombombardment mass spectrometry (FAB-MS). The structure of thesingle product obtained from n-ictyl -glucoside was determinedto be the 2–6 sialylated glucoside. Competition experimentswith n-octyl lactoside and lactosylceramide and gangliosideGal1-3GalNAc1-4(NeuAc2–3)Gal1–4Glcbeeta1–1Cer(GM1) as acceptors for sialyltransferases suggested that SAT-I[NeuAc2–3Gal1–4Glc1-1Cer (GM3) synthase] was atleast in least in part responsible for the 2–3 sialylationof n-octyl lactoside. alkylgalactosides alkylglucosides alkyllactosides neoglycolipids sialytransferases     

Unusual degradation of alpha -beta complexes in Xenopus oocytes by beta -subunits of Xenopus gastric H-K-ATPase

The catalytic -subunit of oligomeric P-type ATPases such asNa-K-ATPase and H-K-ATPase requires association with a -subunit after synthesis in the endoplasmic reticulum (ER) to become stably expressed and functionally active. In this study, we have expressed the-subunit of Xenopus gastricH-K-ATPase (HK) in Xenopus oocytes together with -subunits of H-K-ATPase (HK) or Na-K-ATPase (NK) and have followed the biosynthesis, assembly, and cell surface expression of functional pumps. Immunoprecipitations ofXenopus HK from metabolicallylabeled oocytes show that it is well expressed and, when synthesizedwithout -subunits, can leave the ER and become fully glycosylated.Xenopus HK can associate with both coexpressed HK and NK, but the - complexes formed aredegraded rapidly in or close to the ER and do not produce functionalpumps at the cell surface as assessed by⁸⁶Rb uptake. A possibleexplanation of these results is thatXenopus HK may contain atissue-specific signal that is important in the formation or correcttargeting of functional - complexes in the stomach but thatcannot be recognized in Xenopusoocytes and in consequence leads to cellular degradation of the -complexes in this experimental system.

     

Effect of light treatment and endogenous growth hormones on {alpha}-and {beta}-amylase activities in cotyledons of Phaseolus vulgaris L.

The influence of light and endogenous plant-growth regulatorson the evolution of - and ß-amylases in cotyledonsof Phaseolus vulgaris L. was investigated. Both enzymes, whichare not present in ungerminated seeds, appear during germinationof intact seedlings or incubation of excised cotyledons. -Amylaseactivity decreases upon exposure to light. This inhibition iscorrelated with a drastic increase in chlorophyll content anda change in the endogenous gibberellin-inhibitor balance. ß-Amylaseactivity was not affected by light treatment but was by thepresence of endogenous cytokinins. (Received February 3, 1977; )     

Distribution of Glycosidases and Acid Invertase Activities in Relation to Elongation Growth in Pearl Millet Internode

The mean cell length along a differentiating internode and alliedchanges in the activities of ß-glucosidase, - andß-galactosidase. -mannosidase and acid invertase,together with the contents of reducing and non-reducing sugars,were examined in pearl millet (Pennisetum americanum L. Leekecv. BJ-104). The specific activities of cytoplasmic -mannosidase,wall ß-glucosidase, and cytoplasmic and wall acidinvertase showed close relationships with the rate of cell elongation.The linear regressions of the rate of cell elongation, and thespecific activities of wall ß-glucosidase and cytoplasmicand wall invertase showed significant positive correlations(P<0·05), whereas cytoplasmic -mannosidase was negativelycorrelated (P<0·01). The results are discussed in the light of cell wall looseningand the provision of carbon substrates for cell elongation. Key words: Glycosidases, acid invertase, sugars, cell elongation, Pennisetum americanum L., Leeke     

A Reanalysis of the Kinetics of 14C Photosynthate Translocation in Morning Glory Vines

The spatial and temporal profiles of ¹⁴C photosynthate observedafter a 5 min pulse-labelling period in morning glory vinesare examined. In these experiments a peak of radioactivity appearsto travel down the stem, growing shorter and broader with timeand distance. It is possible to fit the known data reasonably well with aHorwitz reversible-loss model in which the observed changesin peak height and width are attributed to the reversible exchangeof tracer molecules between the translocating sieve tube anda stationary reservoir. The parameters that determine the spatialand temporal profiles are the input kinetics, the sap velocity,v, the ratio of the reservoir volume to sieve tube volume, ,and the permeability to radius ratio, P/r. Even when the inputkinetics are known it is possible to obtain several equallygood fits to the observed tracer profiles with different combinationsof v, , and P/r. With our present state of knowledge it is notpossible to characterize these parameters uniquely, and it isunlikely that tracer techniques alone will yield definite valuesfor v, , and P/r. Ipomoea oil Roth, morning glory, translocation profiles, Horwitz reversible-loss model, mathematical models     

Sugar-Controlled Ca2+ Uptake and {alpha}-Amylase Secretion in Cultured Cells of Rice (Oryza sativa L.)

Sugar starvation-induced synthesis and extracellular liberationof -amylase molecules in suspension-cultured cells of rice (Oryzasativa L.) required Ca²⁺, although the level of translatable-amylase mRNA was not affected in the presence of Ca²⁺. Sugardepletion markedly stimulated Ca²⁺ uptake by rice cells andsucrose supplementation reduced it. Immunohistochemical andelectron probe microanalyzer studies indicated an apparent resemblancebetween the distribution pattern of Ca²⁺ and that of -amylasemolecules induced in the sugar-depleted cells. Ca²⁺ uptake wasreduced by sucrose, maltose, fructose, and glucose similarlyat more than 5 mM, but was unaffected by mannitol (88 mM), 6-deoxy-D-glucose(10 mM), and 3-O-methyl-D-glucose (10 mM). Furthermore, an effectiveCa²⁺ channel blocker, La³⁺ significantly inhibited the Ca²⁺uptake and the synthesis and extracellular liberation of -amylasemolecules in the absence of sucrose, while a general P-typeATPase inhibitor, vanadate greatly stimulated both in the presenceof sucrose. We concluded that, by controlling the Ca²⁺ uptake,metabolic sugars regulate the protein synthesis and posttranslationalsecretory processes of -amylase molecules in rice cells. ⁴ Invited research fellow of the Japan Society for the Promotionof Science. Present address: Plant Physiology Department, WarsawAgricultural University, Rakowiecka Str. 26/30 02-528 Warsaw,Poland.     

Glycosidases from Cotyledons of Pisum sativum L.

-Mannosidase and ß-N-acetylglucosaminidase were purifiedfrom extracts of cotyledons of germinating Pisum sativum L.A 13-fold purification of a-mannosidase free from ß-N-acetylglucosaminidaseactivity was achieved by precipitation in ammonium sulphate,column chromatography on DEAE-cellulose, and treatment with2 M pyridine. ß-N-Acetylglucosaminidase was purified200-fold by the use of (NH₄)₂SO₄, and chromatography on ConcanavalinA¹-Sepharose and Sephacryl-200. This preparation showed no measurablecontamination by -mannosidase activity. Both glycosidases appearto be glycoproteins and demonstrate optimal activity at pH valuesof 4.0–4.5. Both glycosidases appear to have very similarmolecular weights, with -mannosidase being slightly larger thanß-N-acetylglucosaminidase. An extensive search forthe activity of aspartylglycosylamine amido hydrolase in peacotyledons proved unsuccessful.