scholarly journals ANTIGEN RECOGNITION AND THE IMMUNE RESPONSE

1972 ◽  
Vol 136 (2) ◽  
pp. 387-391 ◽  
Author(s):  
Sefik S. Alkan ◽  
Maurice E. Bush ◽  
Danute E. Nitecki ◽  
Joel W. Goodman
Keyword(s):  
Immune Response ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Carboxyl Group ◽  
Amino Group ◽  
Structural Requirements ◽  
Phenolic Ring ◽  
Cellular Immune ◽  
Charged Group

The low molecular weight compound L-tyrosine-azobenzenearsonate (RAT) induces a cellular immune response in guinea pigs. The contribution of the side chain of tyrosine to the immunogenicity of RAT and the structural requirements at that position for immunogenicity were assessed by synthesizing a series of analogs of RAT containing modifications in the side chain of tyrosine and employing them as immunogens. Removal of either the carboxyl or amino group did not markedly affect immunogenicity, measured by the induction of delayed cutaneous sensitivity, whereas deletion of both completely abolished it. However, a charged group was not required since side chains containing a polar hydroxyl group could substitute for chains bearing an amino or carboxyl group. The size of the side chain exerted a pronounced influence; the charged or polar substituent had to be extended from the phenolic ring by at least two carbon atoms in order to confer immunogenicity.

Azoverdin -an Isopyoverdin

1996 ◽  
Vol 51 (11-12) ◽  
pp. 772-780 ◽  
Author(s):  
R Michalke ◽  
K Taraz ◽  
H Budzikiewiez
Keyword(s):  
Carboxylic Acid ◽  
Succinic Acid ◽  
Peptide Chain ◽  
Side Chain ◽  
Carboxyl Group ◽  
Amino Group ◽  
Present Evidence ◽  
N Terminus

For azoverdin, the siderophore of Azomonas macrocytogenes ATCC 12334, a pyoverdintype structure has been suggested. We now present evidence that it is actually an isopyoverdin. Also the sequence of the peptide chain has to be revised. Azoverdin comprises, therefore, the chromophore (3S)-5-amino-1,2-dihydro-8,9-dihydroxy-3H -pyrimido[1,2a]quinoline- 3-carboxylic acid whose amino group is bound to a succinamide residue while the carboxyl group is attached to the N -terminus of L-Hse-[2-(R-1-amino-3-hydroxypropyl)-3,4,5,6- tetrahydropyrimidine-65-carboxylic acid]-N5-acetyl-N5,-hydroxy-ᴅ-Orn-ᴅ-Ser-N5-acetyl-N5- hydroxy-ʟ-Orn. In addition to azoverdin congeners with succinic acid (azoverdin A ) and with ʟ-Glu (azoverdin G ), resp., instead of the succinamide side chain could be isolated.

scholarly journals Structural requirements for the utilization of ascorbate analogues in the prolyl 4-hydroxylase reaction

1994 ◽  
Vol 300 (1) ◽  
pp. 75-79 ◽  
Author(s):  
G Tschank ◽  
J Sanders ◽  
K H Baringhaus ◽  
F Dallacker ◽  
K I Kivirikko ◽  
...  
Keyword(s):  
Negative Charge ◽  
Substrate Inhibition ◽  
Side Chain ◽  
Structural Requirements ◽  
Response Behaviour ◽  
Structural Analogues ◽  
Microsomal Hydroxylation ◽  
Ring Position ◽  
Charged Group ◽  
Positively Charged

The ability of structural analogues of ascorbate to serve as substitutes for this reducing agent in the prolyl 4-hydroxylase reaction was studied. In experiments using the purified enzyme, variations of the compounds′ side chain were compatible with co-substrate activity. The presence of very large hydrophobic substituents or a positively charged group caused an increase in the observed Km values. A negative charge and smaller modifications did not change the affinity to the enzyme when compared with L-ascorbate. 6-Bromo-6-deoxy-L-ascorbate had a lower Km than the physiological reductant. Substitution at the -OH group in ring position 3 prevented binding to the enzyme. The same pattern of activity was observed when the full and uncoupled prolyl 4-hydroxylase reactions were studied. The Vmax. values with all compounds were similar. The reaction of microsomal prolyl 4-hydroxylase was supported by D-isoascorbate, O6-tosyl-L-ascorbate and 5-deoxy-L-ascorbate, giving the same dose-response behaviour as L-ascorbate itself. Again, 6-bromo-6-deoxy-L-ascorbate gave a lower Km and a similar Vmax. value. L-Ascorbic acid 6-carboxylate produced substrate inhibition at concentrations above 0.3 mM. The Km and Vmax. values calculated from concentrations up to 0.2 mM were similar to those of L-ascorbate. The enzyme activity observed with 6-amino-6-deoxy-L-ascorbate was very low in the microsomal hydroxylation system. The calculated Vmax. value was lower than that of L-ascorbate, suggesting a restriction of the access of this compound to the enzyme.

scholarly journals ANTIGEN RECOGNITION AND THE IMMUNE RESPONSE

1972 ◽  
Vol 135 (6) ◽  
pp. 1228-1246 ◽  
Author(s):  
Sefik S. Alkan ◽  
E. Brady Williams ◽  
Danute E. Nitecki ◽  
Joel W. Goodman
Keyword(s):  
Immune Response ◽  
Humoral Immunity ◽  
Cellular Immunity ◽  
Antibody Production ◽  
Guinea Pigs ◽  
Antigen Recognition ◽  
Side Chain ◽  
Carboxyl Group ◽  
Self Help

L-Tyrosine azobenzene-p-arsonate (RAT) induced cellular immunity without antibody production in guinea pigs. Bifunctional antigens were prepared consisting of one RAT carrier moiety linked either directly to a dinitrophenyl (DNP) haptenic determinant or through one or more 6-amino-caproyl (SAC) spacers. Each SAC unit has an extended span of 8 A. Guinea pigs immunized with these conjugates developed cellular immunity directed against the RAT determinant and antibody specific for the DNP determinant. The anti-DNP response was the same with one or three SAC spacers, but was significantly weaker when the two determinants were joined without a spacer. Animals immunized with either DNP-SAC-TYR or DNP-TYR developed neither cellular nor humoral immunity. Prior immunization with RAT potentiated the secondary anti-hapten response to DNP-SAC-RAT. Modification of RAT at either the arsonate or tyrosine positions showed that other charged groups (sulfonate and trimethylammonium) could substitute for arsonate without loss of immunogenicity. Removal of either the amino or carboxyl group from the side chain of tyrosine did not abolish immunogenicity, but immunogenicity was lost upon removal of both. Immunization with symmetrical bifunctional RAT-(SAC)n-RAT and cyclo-(L-RAT-D-RAT) antigens led to cellular immunity but no anti-arsonate antibody, suggesting a barrier to "self-help." These compounds were also ineffective in inducing a secondary anti-arsonate response in animals primed with arsonate-BSA conjugates and RAT.

Specificity of the transport system for neutral amino acids in the hamster intestine

1962 ◽  
Vol 202 (5) ◽  
pp. 919-925 ◽  
Author(s):  
Edmund C. C. Lin ◽  
Hiroshi Hagihira ◽  
T. Hastings Wilson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Transport System ◽  
Side Chain ◽  
Carboxyl Group ◽  
Amino Group ◽  
Methyl Group ◽  
Neutral Amino Acids ◽  
Active Transport System ◽  
Everted Sacs

The specificity of the active transport system for neutral amino acids has been studied with everted sacs of hamster intestine. Amino acids with modifications or replacements of the carboxyl, amino, or α-hydrogen groups were poorly transported and were poor inhibitors of the transport of other l-amino acids. The carboxyl group must remain free, the amino group must not be in the tertiary or quaternary state, and the α-hydrogen can not be replaced by a methyl group without serious effect on the transport rate. It was concluded that the l-amino acids were distinguished from the d-isomers by the interaction of the carrier with the carboxyl group, the amino group, and the α-hydrogen. The side chain of the amino acid must be nonpolar but there is relatively little restriction on its structure.

scholarly journals Anachelin, the Siderophore of the Cyanobacterium Anabaena cylindrica CCAP 1403/2A

2000 ◽  
Vol 55 (9-10) ◽  
pp. 681-687 ◽  
Author(s):  
Hans Beiderbeck ◽  
Kambiz Taraz ◽  
Herbert Budzikiewicz ◽  
Anthony E. Walsby
Keyword(s):  
Salicylic Acid ◽  
Hydroxyl Group ◽  
Carboxyl Group ◽  
Amino Group ◽  
Anabaena Cylindrica ◽  
C Terminus ◽  
N Terminus ◽  
Cyanobacterium Anabaena

Abstract A catecholate siderophore - anachelin - has been isolated from the cyanobacterium Anabaena cylindrica CCAP 1403/2A. The central part of the siderophore is a tripeptide consisting of ʟ-Thr, ᴅ-Ser and ʟ-Ser. Its C-terminus is linked amidically to a 1,1-dimethyl-3-amino-1,2,3,4-tetrahydro-7,8-dihydroxyquinolinium system and its N-terminus to 6-amino-3,5,7-trihydroxyheptanoic acid. The 7-hydroxyl group of the latter is esterified with salicylic acid whose carboxyl group is condensed with the 6-amino group to an oxazoline ring. Anachelin is the first genuine siderophore of a cyanobacterium whose structure has been elucidated.

Reaction of Alantolactone, an Allergenic Sesquiterpene Lactone, with some Amino Acids. Resultant Loss of Immunologic Reactivity

1974 ◽  
Vol 52 (7) ◽  
pp. 575-581 ◽  
Author(s):  
G. Dupuis ◽  
J. C. Mitchell ◽  
G. H. N. Towers
Keyword(s):  
Amino Acids ◽  
Contact Dermatitis ◽  
Sesquiterpene Lactone ◽  
Sesquiterpene Lactones ◽  
Sulfhydryl Group ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Amino Group ◽  
Michael Type Addition ◽  
Methylene Group

A study of the reaction of a hapten, alantolactone, with some amino acids is reported. Previously, we have reported than an α-methylene group attached to the γ-lactone is the immunologic requisite of alantolactone and some other sesquiterpene lactones. Such a group is known to be capable of undergoing "Michael-type addition" with the sulfhydryl group of cysteine. We confirm this finding and report that alantolactone can also undergo addition with the imidazole group of histidine and with the ε-amino group of lysine, but not with the guanido group of arginine, the hydroxyl group of serine, or the thio ether function of methionine. We selected these amino acids for further study because of their nucleophilic side chain. Samples of alantolactone that have undergone such addition no longer produce allergic eczematous contact dermatitis, as measured by patch test.

scholarly journals Sortase C-Mediated Anchoring of BasI to the Cell Wall Envelope of Bacillus anthracis

2007 ◽  
Vol 189 (17) ◽  
pp. 6425-6436 ◽  
Author(s):  
Luciano A. Marraffini ◽  
Olaf Schneewind
Keyword(s):  
Cell Wall ◽  
Bacillus Anthracis ◽  
Active Site ◽  
Diaminopimelic Acid ◽  
Side Chain ◽  
Carboxyl Group ◽  
Amino Group ◽  
Active Site Cysteine ◽  
New Hosts ◽  
Host Death

ABSTRACT Vegetative forms of Bacillus anthracis replicate in tissues of an infected host and precipitate lethal anthrax disease. Upon host death, bacilli form dormant spores that contaminate the environment, thereby gaining entry into new hosts where spores germinate and once again replicate as vegetative forms. We show here that sortase C, an enzyme that is required for the formation of infectious spores, anchors BasI polypeptide to the envelope of predivisional sporulating bacilli. BasI anchoring to the cell wall requires the active site cysteine of sortase C and an LPNTA motif sorting signal at the C-terminal end of the BasI precursor. The LPNTA motif of BasI is cleaved between the threonine (T) and the alanine (A) residue; the C-terminal carboxyl group of threonine is subsequently amide linked to the side chain amino group of diaminopimelic acid within the wall peptides of B. anthracis peptidoglycan.

Specificity of carnitine action on fatty acid oxidation by heart muscle

1962 ◽  
Vol 202 (1) ◽  
pp. 117-121 ◽  
Author(s):  
Irving B. Fritz ◽  
Eli Kaplan ◽  
Kenneth T. N. Yue
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Heart Muscle ◽  
Hydroxyl Group ◽  
Acid Oxidation ◽  
Carboxyl Group ◽  
Amino Group ◽  
Long Chain Fatty Acids ◽  
Optimal Conditions ◽  
Long Chain

Carnitine (ß-hydroxy, γ-trimethylammonium butyrate), at concentrations of 10–5 m and more, increased the oxidation of long-chain fatty acids severalfold by heart muscle particulates incubated under optimal conditions. CoA dependency could be demonstrated in the presence of carnitine but not in its absence. Of a variety of compounds tested for carnitinelike activity, only acetylcarnitine and ß-hydroxy, γ-dimethylaminobutyrate ("norcarnitine") influenced palmitate oxidation in the assay system. Activity was abolished by removal of the hydroxyl group on the ß carbon; by replacement of the carboxyl group with either a cyano, an alcohol, or an amide grouping; or by substitution of an amino group for the trimethylammonium moiety of the molecule. Nonspecifically tritium-labeled carnitine was not degraded by heart particulates during incubation, indicating that carnitine acted catalytically to enhance fatty acid oxidation. The physiological significance of the data was discussed.

Recognition of β-lactam antibiotics by rat peptide transporters, PEPT1 and PEPT2, in LLC-PK1 cells

1997 ◽  
Vol 273 (5) ◽  
pp. F706-F711 ◽  
Author(s):  
Tomohiro Terada ◽  
Hideyuki Saito ◽  
Mayumi Mukai ◽  
Ken-Ichi Inui
Keyword(s):  
Phenyl Ring ◽  
Inhibition Constant ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Amino Group ◽  
Inhibitory Effects ◽  
Peptide Transporters

PEPT1 and PEPT2 are H+-coupled peptide transporters expressed preferentially in the intestine and kidney, respectively, which mediate uphill transport of oligopeptides and peptide-like drugs such as β-lactam antibiotics. In the present study, we have compared the recognition of β-lactam antibiotics by LLC-PK1 cells stably transfected with PEPT1 or PEPT2 cDNA. Cyclacillin (aminopenicillin) and ceftibuten (anionic cephalosporin without an α-amino group) showed potent inhibitory effects on the glycylsarcosine uptake in the PEPT1-expressing cells. Other β-lactams, such as cephalexin, cefadroxil, and cephradine (aminocephalosporins), inhibited modestly the PEPT1-mediated glycylsarcosine uptake. Except for ceftibuten, these β-lactams showed much more potent inhibitions on the glycylsarcosine uptake via PEPT2 than via PEPT1. Comparison of the inhibition constant ( K i) values between cefadroxil and cephalexin suggested that the hydroxyl group at the NH2-terminal phenyl ring increased affinity for both PEPT1 and PEPT2. It is concluded that PEPT2 has a much higher affinity for β-lactam antibiotics having an α-amino group than PEPT1 and that substituents at the NH2-terminal side chain of these drugs are involved in the recognition by both peptide transporters.

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