scholarly journals Comparative rates of transfer of N-acetylneuraminic acid to acceptors bearing one or more Gal(β 1-4)GlcNAc terminus by the Gal(β 1-4)GlcNAc(NeuAc-Gal) (α 2-6)-sialyltransferase from embryonic chicken liver. Utilization of oligosaccharides as acceptors in sialyltransferase assays

1983 ◽  
Vol 213 (1) ◽  
pp. 253-260 ◽  
Author(s):  
B Bendiak ◽  
G M W Cook
Keyword(s):  
Relative Orientation ◽  
Chicken Liver ◽  
Acid Glycoprotein ◽  
Acetylneuraminic Acid ◽  
Embryonic Chicken ◽  
Acid Protein ◽  
Marked Preference ◽  
Km Value ◽  
Glcnac Termini

Using a number of branched and unbranched oligosaccharides, glycoproteins and artificial glycoproteins bearing Gal(beta 1-4)GlcNAc-R termini as acceptors (where R represents H, oligosaccharide, oligosaccharide-protein or fatty acid-protein), the comparative rates of transfer of NeuAc by the Gal(beta 1-4)GlcNAc(NeuAc-Gal) (alpha 2-6)-sialyltransferase of embryonic chicken liver were determined. Acceptor substrates were utilized at levels approximating physiological, near the Km value of the best acceptor, desialylated alpha 1 acid glycoprotein. The sialyltransferase has a marked preference for multi-branched acceptors. From the specificity data, it is concluded that the enzyme binds at least two Gal(beta 1-4)GlcNAc termini of an acceptor molecule, and that the relative orientation of the branches is an important factor determining the rate of catalysis by the enzyme. The use of oligosaccharides as acceptors to study sialyltransferase catalyses is emphasized. Results are discussed in the context of the mode of assembly of sialoside termini of known glycoprotein structures in vivo.

The specificity of sialyltransferase activity in smooth membrane fractions of embryonic chicken liver

1981 ◽  
Vol 59 (3) ◽  
pp. 171-180 ◽  
Author(s):  
Brad Bendiak ◽  
Sara E. Zalik
Keyword(s):  
Marker Enzyme ◽  
Temperature Optimum ◽  
Ph Optimum ◽  
Acid Glycoprotein ◽  
Acetylneuraminic Acid ◽  
Sialyltransferase Activity ◽  
Acceptor Specificity ◽  
Embryonic Chicken ◽  
Smooth Membrane ◽  
Triton X

Smooth membrane preparations of 13-day embryonic chicken livers, characterized by electron microscopy and marker enzyme analyses, have been found to contain sialyltransferase activity which displayed precise acceptor specificity. One sialyltransferase transferred N-acetylneuraminic acid (NANA) to galβ1 → 4glcNAcβ1 → R structures. Evidence based on competition studies suggests that a second enzyme is present transferring this sugar to a galβ1 → 3galNAcα1 → R structure. The enzyme capable of adding NANA to galβ1 → 4glcNAcβ1 → R structures has a pH optimum of 5.5, a temperature optimum of 30 °C, and half-saturating values of 17 μM for CMP-NANA and 180 μM for galactoside termini on desialyzed α1-acid glycoprotein. It is activated about 10-fold by Triton X-100, has no exogenous divalent cation requirement, and is inhibited by CTP, CDP, and CMP. The enzyme requires carbohydrate structures underlying the galβ1 → 4glcNAc terminus for maximal catalytic activity; the necessity of such precise specificities of sialyltransferases is discussed in the light of recent structural evidence for the carbohydrate moieties of several glycoproteins.

scholarly journals LASS3 (longevity assurance homologue 3) is a mainly testis-specific (dihydro)ceramide synthase with relatively broad substrate specificity

2006 ◽  
Vol 398 (3) ◽  
pp. 531-538 ◽  
Author(s):  
Yukiko Mizutani ◽  
Akio Kihara ◽  
Yasuyuki Igarashi
Keyword(s):  
Amino Acid ◽  
Substrate Specificity ◽  
Family Members ◽  
Fatty Acyl ◽  
Ceramide Synthase ◽  
Broad Substrate Specificity ◽  
Acid Protein ◽  
Amino Acid Protein

The LASS (longevity assurance homologue) family members are highly conserved from yeasts to mammals. Five mouse and human LASS family members, namely LASS1, LASS2, LASS4, LASS5 and LASS6, have been identified and characterized. In the present study we cloned two transcriptional variants of hitherto-uncharacterized mouse LASS3 cDNA, which encode a 384-amino-acid protein (LASS3) and a 419-amino-acid protein (LASS3-long). In vivo, [3H]dihydrosphingosine labelling and electrospray-ionization MS revealed that overproduction of either LASS3 isoform results in increases in several ceramide species, with some preference toward those having middle- to long-chain-fatty acyl-CoAs. A similar substrate preference was observed in an in vitro (dihydro)ceramide synthase assay. These results indicate that LASS3 possesses (dihydro)ceramide synthesis activity with relatively broad substrate specificity. We also found that, except for a weak display in skin, LASS3 mRNA expression is limited almost solely to testis, implying that LASS3 plays an important role in this gland.

In vivo modulated N -acyl side chain of N -acetylneuraminic acid modulates the cell contact-dependent inhibition of growth

FEBS Letters ◽  
1996 ◽  
Vol 395 (2-3) ◽  
pp. 170-173 ◽  
Author(s):  
J.Raimund Wieser ◽  
Anja Heisner ◽  
Peer Stehling ◽  
Franz Oesch ◽  
Werner Reutter
Keyword(s):  
Side Chain ◽  
Cell Contact ◽  
Acetylneuraminic Acid ◽  
Inhibition Of Growth ◽  
Acyl Side Chain ◽  
Dependent Inhibition

Porcine Sugar Nucleotide: Glycoprotein Glycosyltransferases. I. Blood Serum and Liver Sialyltransferase

1971 ◽  
Vol 49 (7) ◽  
pp. 829-837 ◽  
Author(s):  
Roger L. Hudgin ◽  
Harry Schachter
Keyword(s):  
Sialic Acid ◽  
High Speed ◽  
Liver Homogenate ◽  
Acetone Powder ◽  
Acid Glycoprotein ◽  
Acetylneuraminic Acid ◽  
Pork Liver ◽  
Terminal Galactose ◽  
And Function ◽  
Powder Extract

The properties of CMP-N acetylneuraminic acid: glycoprotein sialyltransferase have been studied in pork serum, a crude pork liver homogenate, and a soluble acetone powder extract prepared from pork liver. Whereas the crude liver homogenate enzyme is activated by the detergent Triton X-100, this detergent has no effect on the activities of either serum or acetone powder extract; since high-speed centrifugation does not sediment the enzyme activities of the latter two preparations, it is concluded that they are soluble. Comparison of the membrane-bound and soluble liver enzymes indicates that the membrane modifies kinetic behavior only to a limited extent. In both liver and serum, a single sialyltransferase is responsible for incorporation of sialic acid into α1-acid glycoprotein, fetuin, and N-acetyllactosamine, and sialic acid incorporation occurs whenever a terminal galactose linked (β, 1 → 4) to a penultimate N-acetylglucosamine is presented to the enzyme. Although the serum enzyme resembles the liver enzyme, both the source and function of serum sialyltransferase are unknown.

scholarly journals The Lst Sialyltransferase of Neisseria gonorrhoeae Can Transfer Keto-Deoxyoctanoate as the Terminal Sugar of Lipooligosaccharide: a Glyco-Achilles Heel That Provides a New Strategy for Vaccines to Prevent Gonorrhea

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Freda E.-C. Jen ◽  
Margaret R. Ketterer ◽  
Evgeny A. Semchenko ◽  
Christopher J. Day ◽  
Kate L. Seib ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Neisseria Gonorrhoeae ◽  
Phase Variation ◽  
Multidrug Resistant ◽  
Content Type ◽  
Acetylneuraminic Acid ◽  
New Strategy ◽  
Opsonophagocytic Killing ◽  
Further Development

ABSTRACT The lipooligosaccharide (LOS) of Neisseria gonorrhoeae plays key roles in pathogenesis and is composed of multiple possible glycoforms. These glycoforms are generated by the process of phase variation and by differences in the glycosyltransferase gene content of particular strains. LOS glycoforms of N. gonorrhoeae can be terminated with an N-acetylneuraminic acid (Neu5Ac), which imparts resistance to the bactericidal activity of serum. However, N. gonorrhoeae cannot synthesize the CMP-Neu5Ac required for LOS biosynthesis and must acquire it from the host. In contrast, Neisseria meningitidis can synthesize endogenous CMP-Neu5Ac, the donor molecule for Neu5Ac, which is a component of some meningococcal capsule structures. Both species have an almost identical LOS sialyltransferase, Lst, that transfers Neu5Ac from CMP-Neu5Ac to the terminus of LOS. Lst is homologous to the LsgB sialyltransferase of nontypeable Haemophilus influenzae (NTHi). Studies in NTHi have demonstrated that LsgB can transfer keto-deoxyoctanoate (KDO) from CMP-KDO to the terminus of LOS in place of Neu5Ac. Here, we show that Lst can also transfer KDO to LOS in place of Neu5Ac in both N. gonorrhoeae and N. meningitidis. Consistent with access to the pool of CMP-KDO in the cytoplasm, we present data indicating that Lst is localized in the cytoplasm. Lst has previously been reported to be localized on the outer membrane. We also demonstrate that KDO is expressed as a terminal LOS structure in vivo in samples from infected women and further show that the anti-KDO monoclonal antibody 6E4 can mediate opsonophagocytic killing of N. gonorrhoeae. Taken together, these studies indicate that KDO expressed on gonococcal LOS represents a new antigen for the development of vaccines against gonorrhea. IMPORTANCE The emergence of multidrug-resistant N. gonorrhoeae strains that are resistant to available antimicrobials is a current health emergency, and no vaccine is available to prevent gonococcal infection. Lipooligosaccharide (LOS) is one of the major virulence factors of N. gonorrhoeae. The sialic acid N-acetylneuraminic acid (Neu5Ac) is present as the terminal glycan on LOS in N. gonorrhoeae. In this study, we made an unexpected discovery that KDO can be incorporated as the terminal glycan on LOS of N. gonorrhoeae by the alpha-2,3-sialyltransferase Lst. We showed that N. gonorrhoeae express KDO on LOS in vivo and that the KDO-specific monoclonal antibody 6E4 can direct opsonophagocytic killing of N. gonorrhoeae. These data support further development of KDO-LOS structures as vaccine antigens for the prevention of infection by N. gonorrhoeae.

scholarly journals A drug candidate for treating adverse reactions caused by pathogenic antibodies inducible by COVID-19 virus and vaccines

2021 ◽  
Author(s):  
Huiru Wang ◽  
Xiancong Wu ◽  
Yuekai Zhang ◽  
Qiuchi Chen ◽  
Lin Dai ◽  
...  
Keyword(s):  
Adverse Reactions ◽  
Acid Methyl Ester ◽  
Drug Candidate ◽  
Lung Epithelium ◽  
Acetylneuraminic Acid ◽  
Excellent Safety Profile ◽  
Pathogenic Antibodies ◽  
Epithelium Cells ◽  
Unique Mechanism

In a previous study, we reported that certain anti-spike antibodies of COVID-19 and SARS-CoV viruses can have a pathogenic effect through binding to sick lung epithelium cells and misleading immune responses to attack self-cells. We termed this new pathogenic mechanism Antibody Dependent Auto-Attack (ADAA). This study explores a drug candidate for prevention and treatment of such ADAA-based diseases. The drug candidate is a formulation comprising N-acetylneuraminic acid methyl ester (NANA-Me), an analog of N-acetylneuraminic acid. NANA-Me acts through a unique mechanism of action (MOA) which is repairment of the missing sialic acid on sick lung epithelium cells. This MOA can block the antibody binding to sick cells, which are vulnerable to pathogenic antibodies. Our in vivo data showed that the formulation significantly reduced the sickness and deaths caused by pathogenic anti-spike antibodies. Therefore, the formulation has the potential to prevent and treat the serious conditions caused by pathogenic antibodies during a COVID-19 infection. In addition, the formulation has potential to prevent and treat the adverse reactions of COVID-19 vaccines because the vaccines can induce similar antibodies, including pathogenic antibodies. The formulation will be helpful in increasing the safety of the vaccines without reducing the vaccine efficacy. Compared to existing antiviral drugs, the formulation has a unique MOA of targeting receptors, broad spectrum of indications, excellent safety profile, resistance to mutations, and can be easily produced.

scholarly journals Sialic Acid and Sialylated Oligosaccharide Supplementation during Lactation Improves Learning and Memory in Rats

Nutrients ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1519 ◽  
Author(s):  
Elena Oliveros ◽  
Enrique Vázquez ◽  
Alejandro Barranco ◽  
María Ramírez ◽  
Agnes Gruart ◽  
...  
Keyword(s):  
Cognitive Abilities ◽  
Behavioral Assessment ◽  
Long Term Potentiation ◽  
Cognitive Outcomes ◽  
Free Form ◽  
Control Group ◽  
Adult Rats ◽  
Acetylneuraminic Acid ◽  
One Year

Sialic acids (Sia) are postulated to improve cognitive abilities. This study evaluated Sia effects on rat behavior when administered in a free form as N-acetylneuraminic acid (Neu5Ac) or conjugated as 6′-sialyllactose (6′-SL). Rat milk contains Sia, which peaks at Postnatal Day 9 and drops to a minimum by Day 15. To bypass this Sia peak, a cohort of foster mothers was used to raise the experimental pups. A group of pups received a daily oral supplementation of Neu5Ac to mimic the amount naturally present in rat milk, and another group received the same molar amount of Sia as 6′-SL. The control group received water. After weaning, rats were submitted to behavioral evaluation. One year later, behavior was re-evaluated, and in vivo long-term potentiation (LTP) was performed. Brain samples were collected and analyzed at both ages. Adult rats who received Sia performed significantly better in the behavioral assessment and showed an enhanced LTP compared to controls. Within Sia groups, 6′-SL rats showed better scores in some cognitive outcomes compared to Neu5Ac rats. At weaning, an effect on polysialylated-neural cell adhesion molecule (PSA-NCAM) levels in the frontal cortex was only observed in 6′-SL fed rats. Providing Sia during lactation, especially as 6′-SL, improves memory and LTP in adult rats.

scholarly journals Evidence for heterophilic adhesion of embryonic retinal cells and neuroblastoma cells to substratum-adsorbed NCAM

1992 ◽  
Vol 117 (6) ◽  
pp. 1311-1320 ◽  
Author(s):  
BA Murray ◽  
JJ Jensen
Keyword(s):  
Neuroblastoma Cells ◽  
Cell Types ◽  
Antibody Fragments ◽  
Adhesion Assay ◽  
Temperature Dependent ◽  
Retinal Cells ◽  
Embryonic Chicken ◽  
Surface Ligand ◽  
Solid Substratum

The adhesion of embryonic chicken retinal cells and mouse N2A neuroblastoma cells to purified embryonic chicken retinal NCAM adsorbed on a solid substratum was examined using a quantitative centrifugal adhesion assay. Both cell types adhered to NCAM and the adhesion was specifically inhibited by monovalent anti-NCAM antibody fragments. N2A cell adhesion depended on the amount of NCAM applied to the substratum, was cation independent, and was insensitive to treatment with the cytoskeletal perturbing drugs colchicine and cytochalasin D. These results indicated that the tubulin and actin cytoskeletons were not critically required for adhesion to NCAM and make it unlikely that the cell surface ligand for NCAM is an integrin. Adhesion was however temperature dependent, strengthening greatly after a brief incubation at 37 degrees C. CHO cells transfected with NCAM cDNAs did not adhere specifically to substratum-bound NCAM and pretreatment of N2A cells and retinal cells with anti-NCAM antibodies did not inhibit adhesion to substratum-bound NCAM. These results suggest that a heterophilic interaction between substratum-adsorbed NCAM and a non-NCAM ligand on the surface of the probe cells affects adhesion in this system and support the possibility that heterophilic adhesion may be a function of NCAM in vivo.

α1-Acid glycoprotein expressed in the plasma of chronic myeloid leukemia patients does not mediate significant in vitro resistance to STI571

Blood ◽  
2002 ◽  
Vol 99 (2) ◽  
pp. 713-715 ◽  
Author(s):  
Heather G. Jørgensen ◽  
Moira A. Elliott ◽  
Elaine K. Allan ◽  
Christine E. Carr ◽  
Tessa L. Holyoake ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Plasma Proteins ◽  
Myeloid Leukemia ◽  
Philadelphia Chromosome ◽  
Drug Efficacy ◽  
Acid Glycoprotein ◽  
Proliferation In Vitro ◽  
Normal Controls

Abstract Despite the efficacy of STI571 (Glivec, Novartis, Basle, Switzerland) in treating chronic myeloid leukemia (CML), drug resistance has already been noted both in vitro and in vivo. As plasma proteins, including alpha-1-acid glycoprotein (AGP), may reduce drug efficacy through binding, AGP was investigated for its ability to interact with STI571.  At all stages of CML, AGP plasma level was significantly higher than in normal controls (P < .05). The glycoprotein was purified from normal plasma and individual chronic myeloid leukemia (CML) patients' plasma by low-pressure chromatography. The influence of α1-acid glycoprotein (AGP), in the presence of STI571, on the proliferation of Philadelphia chromosome–positive (Ph+) cells was examined. Normal AGP, even at supraphysiological concentrations, did not block the effect of STI571 on K562-cell proliferation in vitro. Moreover, CML-derived AGP failed to block the effect of STI571 on Ph+ cells in vitro. Thus, these in vitro findings suggest that AGP will not abrogate the antileukemic activity of STI571.

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