LitCovid-sentences  

PMC:7352545 / 19471-26133 JSONTXT 11 Projects

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Id Subject Object Predicate Lexical cue
T183 0-2 Sentence denotes 4.
T184 3-93 Sentence denotes Relationship between C4-O- and C9-O-Acetyl SA Preferences of CoVs in Host Cell Recognition
T185 95-99 Sentence denotes 4.1.
T186 100-127 Sentence denotes General O-Acetylation of SA
T187 128-317 Sentence denotes SAs have various derivatives of more than 50 chemically different structures formed from the basic N-acetylneuraminic acid (Neu5Ac) on the main ring of pyranose and the glycerol side chain.
T188 318-426 Sentence denotes SA are modified by acetyl-, lactyl-, methyl- and sulfo-groups individually or in multiple combinations [28].
T189 427-483 Sentence denotes Multiple enzymes are involved in the modifications [29].
T190 484-622 Sentence denotes Historically, the first discovered SA was crystallized by Gunner Blix via a hot mild acid extraction of bovine submaxillary mucin in 1936.
T191 623-657 Sentence denotes It consisted of two acetyl groups.
T192 658-723 Sentence denotes Among these, only one acetyl group was attached to nitrogen [30].
T193 724-876 Sentence denotes Blix isolated a 9-O-acetyl SA of the common SA N-acetylneuraminic acid (Neu5Ac), chemically described as 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac2).
T194 877-952 Sentence denotes Neu5,9Ac2, Neu5Ac and Neu5Gc are naturally occurring SA species in mammals.
T195 953-992 Sentence denotes A common modification is O-acetylation.
T196 993-1046 Sentence denotes In fact, O-acetylation of SAs is common in organisms.
T197 1047-1216 Sentence denotes The O-acetyl modification occurs in single positions of C-4, C-7, C-8 and C-9 of SA as well as in combined C-positions to yield Neu4,5Ac2, Neu5,9Ac2 and Neu5,7,9Ac3 SAs.
T198 1217-1292 Sentence denotes Neu5Ac9NAc is a chemical and biologic mimic of Neu5,9Ac2 in the SA-glycans.
T199 1293-1423 Sentence denotes The C-7 and/or C-9 O-acetylations are catalyzed by the SA O-acetyltransferase enzyme, Cas1 domain containing 1 (CasD1) (Figure 6).
T200 1424-1529 Sentence denotes CasD1 catalyzes the addition of acetyl groups to the SA C-7 at the late Golgi apparatus compartment [31].
T201 1530-1674 Sentence denotes Thereafter, an enzyme termed “migrase” transfers the additional acetyl-group from C-7 to C-9, although this enzyme has not been identified [29].
T202 1675-1803 Sentence denotes CasD1 uses acetyl-coenzyme A as a donor substrate and CMP-Neu5Ac as an acceptor substrate, but with weak activity on CMP-Neu5Gc.
T203 1804-1958 Sentence denotes Biologically, the SA O-acetylation event confers merits to hosts such as protection from pathogenic invasion and maintenance of systemic self-homeostasis.
T204 1959-2121 Sentence denotes The O-acetylation event of SAs protects the SA-containing glycans from neuraminidase (NA)/sialidase action, because O-acetyl-groups inhibit microbial NA activity.
T205 2122-2221 Sentence denotes The chemical structure of the O-acetyl group is quite unstable and susceptible to esterase enzymes.
T206 2222-2355 Sentence denotes Sialic acid cleavage of the di-acetylated Neu5,7,9Ac3 by bacterial NAs decreases two-fold, when compared to mono-O-acetylated Neu5Ac.
T207 2356-2465 Sentence denotes The O-acetylated glycan modification invites interaction with viruses, antibodies and mammalian lectins [32].
T208 2466-2551 Sentence denotes Therefore, the SA O-acetylation modification confers specific functions to organisms.
T209 2553-2557 Sentence denotes 4.2.
T210 2558-2642 Sentence denotes Evolutionary Acquisition of C4-O-Acetyl and C9-O-Acetyl SA Recognition by HE Enzymes
T211 2644-2650 Sentence denotes 4.2.1.
T212 2651-2675 Sentence denotes C4-O-Acetyl Modification
T213 2676-2790 Sentence denotes For example, in the horse, C4-O-acetyl modification of Neu5Ac (SA) occupies more than 50% of the total SA content.
T214 2791-2865 Sentence denotes The C4-O-acetylated Neu5Ac, Neu4,5Ac2, inhibits the influenza A2 virus HA.
T215 2866-3003 Sentence denotes De-acetylation reagents such as NaOH or NaIO4 treatment completely hemagglutinate Neu4,5Ac2 by elimination of the C4-O-acetyl group [33].
T216 3004-3141 Sentence denotes The C4-O-acetyl Neu5Ac species are found in various sources such as equine erythrocyte GM3, starfish A. rubens and fish [34,35,36,37,38].
T217 3142-3227 Sentence denotes C4-O-acetylated Neu5Ac facilitates the initial attachment of viruses to target cells.
T218 3228-3397 Sentence denotes Like the influenza C virus, infectious salmon anemia virus (ISAV), a member of the Orthomyxoviridae family, contains HE and HEF proteins to mediate virus entry and exit.
T219 3398-3551 Sentence denotes C4-O-Ac Neu5Ac is the major receptor determinant of ISAV in receptor binding and destruction [38], while the influenza C virus recognizes C9-O-Ac Neu5Ac.
T220 3552-3743 Sentence denotes The acetylesterase RDE of ISAV cleaves C4-O-Ac via 4-SA-O-acetylesterase with a short turnover time, whereas C9-O-Ac Neu5Ac is cleaved by 9-SA-O-acetylesterase with a long turnover time [34].
T221 3744-3883 Sentence denotes The position of SA O-acetylation is linked to functions including substrate differentiation of enzymes such as NAs and esterase by C4 O-Ac.
T222 3884-4013 Sentence denotes Previous development of O-Ac site-selective NA inhibitors were based on the conceptual consideration of different O-Ac positions.
T223 4014-4122 Sentence denotes The O-Ac of SAs is site-specific, as C4 of Neu5Ac is considered to be a potential position for modification.
T224 4123-4231 Sentence denotes Historically, inhibitors of influenza A and B viruses-sialidases were designed by Von-Itzstein in 1993 [39].
T225 4232-4341 Sentence denotes The Ac group-based C4 substitution interacts with amino acid Glu-119 present in the active site of sialidase.
T226 4342-4511 Sentence denotes Guanidine-attached C4 of C2–C3 unsaturated SA (Neu5Ac2en) inhibits activity of sialidases isolated from influenza A virus (Singapore/1/57) and B virus (Victoria/102/85).
T227 4512-4646 Sentence denotes The same scenario was applied for sialidase inhibition of the human parainfluenza virus type 3, which has HN and fusion proteins [40].
T228 4647-4725 Sentence denotes The C4 of Neu5Ac2en was substituted by alkyl groups such as the O-ethyl group.
T229 4726-4815 Sentence denotes For example, Zanamivir has a substitution with a 4-guanidino group with an IC50 of 25 μM.
T230 4816-4889 Sentence denotes Thus, sialidase inhibition is important for C4 modification of Neu5Ac2en.
T231 4890-5033 Sentence denotes Later, oseltamivir with the tradename Tamiflu (Basel, Switzerland) and zanamivir with the tradename Relenza (London, UK) were established [41].
T232 5034-5107 Sentence denotes These drugs exhibit some adverse side effects that restrict clinical use.
T233 5109-5115 Sentence denotes 4.2.2.
T234 5116-5143 Sentence denotes SA C9-O-Acetyl Modification
T235 5144-5322 Sentence denotes The SA 9-O-acetylation in hosts allows hosts to evade influenza A virus hemagglutinin (HA) recognition and some lectins of factor H (FH), CD22/Siglec-2 and sialoadhesin/Siglec-1.
T236 5323-5452 Sentence denotes Instead, the influenza C virus HA recognizes the hosts. β-elimination and permethylation eliminate the 9-O-acetyl group from SAs.
T237 5453-5695 Sentence denotes Chemical modification of the C-9 position of Neu5,9Ac2 generates a 9-N-acetyl analog, 9-acetamido-9-deoxy-N-acetylneuraminic acid (Neu5Ac9NAc), a mimic of Neu5,9Ac2 with influenza C virus-binding capacity, which is not cleaved by the HE [42].
T238 5696-5762 Sentence denotes SA O-acetylesterase regulates the presence of 7,9-O-Ac and 9-O-Ac.
T239 5763-5849 Sentence denotes SA O-acetylation and deacetylation are involved in development, cancer and immunology.
T240 5850-5916 Sentence denotes SA O-acetylation alters host lectin bindings such as siglecs [29].
T241 5917-5981 Sentence denotes The presence of 9-O-Ac can also reduce the activity of NAs [43].
T242 5982-6041 Sentence denotes SA modifications regulate pathogen binding or pathogen NAs.
T243 6042-6100 Sentence denotes Influenza A/B/C/D viruses use SA as their entry receptors.
T244 6101-6236 Sentence denotes Influenza A and B subtypes bind to SAs via HA and NA to allow endocytosis of the virus and fusion of the viral envelope with endosomes.
T245 6237-6347 Sentence denotes In contrast, influenza C and D subtypes bear only one coated glycoprotein, termed the HE fusion protein (HEF).
T246 6348-6378 Sentence denotes The HEF acts as the HA and NA.
T247 6379-6566 Sentence denotes HEF recognizes 9-O-acetyl SA for entry into cells, while the esterase domain removes 9-O-acetyl-groups and liberates the virus from mucus and mis-assembled virus aggregates after budding.
T248 6567-6662 Sentence denotes The 9-O-Ac on cells prevents the NA activity and HA binding of the influenza A type virus [44].