Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The specificity of the N- and C-terminal antigenic determinant (P17: sequence Lys1-Cys6-Asn27, Trp123-Cys127-Leu129) of hen egg-white lysozyme (HL) was studied in more detail. In a Scatchard plot of the binding of 14C-acetyl HL with guinea pig purified anti-P17 antibody experimental values bent sharply near r=1. This suggests the presence of two antibody populations with different affinities for HL or possible steric hindrance in the binding of a second HL molecule to the second binding site of the antibody molecule. The antigenic activities of various peptides were tested by measuring their inhibition of the binding of 14C-acetyl-P17 with the anti-P17 antibody. Only P17 and P17t (sequence Lys1-Cys6-Homoser12, Trp123-Cys127-Leu129) were inhibitory, with KI values of 2.0 times 10(4) and 8.1 times 10(3), respectively. These results indicate that the direct binding site of P17 to anti-P17 antibody may be located in the terminal portion of P17 (sequence Lys1-Cys6-Homoser12, Trp123-Cys127-Leu129) while the rest of P17 may be important in maintaining the conformation of this determinant. The single disulphide blood involved in this determinant is essential for manifestation of immunological activity.
 ...
PMID:Further studies on the specificity of the N- and C-terminal antigenic determinant of hen egg-white lysozyme. 5 58

Various small fragments of (see article) which is one of the immunodominant groups of hen egg-white lysozyme (HL), were tested for macrophage migration inhibition (MMI) of peritoneal exudate cells (PEC) from guinea pigs immunized with HL. P17 was split in the middle with cyanogen bromide. The terminal portion of (see article) showed positive MMI, whereas the non-terminal half of P17, P17i (sequence 13-27) only showed very weak MMI activity. A fragment derived from the middle portion of P17, P17m (sequence 11-22), was inactive. When P17 were reduced and alkylated, one of the resultant peptides, P17N (sequence 1-[CM-Cys-6]-27) still has MMI activity with PEC taken from guinea pigs immunized with HL, although no antibody reacting with it was detected, but P17C (sequence 123-[CM-Cys-127]-129) was inactive. The peptides P17 and P17N were both immunogenic in guinea pigs in respect to the delayed hypersensitivity response. Again P17t and P17N were immunodominant groups, but the reactivity of P17i in MMI assay of this group of animals was greater than that in guinea pigs immunized with HL. The reactivities of HL with PEC taken from guinea pigs immunized with P17 or P17N were generally weaker than those of the antigens used for immunization.
 ...
PMID:Antigenic determinants of hen egg-white lysozyme in delayed hypersensitivity. II. Antigenicity and immunogenicity of the N- and C-terminal peptide. 5 72

The delayed-type hypersensitivity (DTH) response of C3H/HeN mice to hen egg white lysozyme (HEL) can be blocked by a single iv injection of a solution of HEL in buffered saline 7 days before sensitization of animals with HEL in complete Freund's adjuvant (CFA). The minimal structure of HEL required for the suppression was examined by determining the abilities of various HEL-derivative peptides to inhibit HEL-DTH. Treatment of normal mice with Ploop I X II, sequence 57-107 (Cys64-Cys80, Cys76-Cys94), or P17 (sequences 1-27 and 123-129 linked by Cys6-Cys127) 7 days before immunization with HEL resulted in marked suppression of the DTH response. This inhibition of DTH involved generation of suppressor T cells (Ts). The results suggested that two suppressor pathways are involved. These data, together with another recent finding (1) that an entirely different portion of HEL is a suppressor determinant (SD) in A/J mice, indicate that different epitopes act as SDs in different strains of mice. Of the loop region peptides tested, Plc (intact loop I joined to a linear peptide, residues 84-97) was found to be the minimum structure capable of suppressing the HEL-DTH response; loop I or II alone did not cause suppression. Activation of Ts cells by the loop peptide depended on its conformational structure; completely reduced and carboxymethylated Ploop I X II did not cause suppression.
 ...
PMID:Suppression of the delayed-type hypersensitivity response to hen egg white lysozyme (HEL) by HEL peptides in a genetically high-responder mouse strain: evidence for requirement of the loop structure for induction of suppressor T cells. 242 6

The carrier determinant in the N- and C-region of hen egg-white lysozyme (lysozyme), recognized by T cells, which helps antibody formation to a single DNP residue bound to the Lysine-33 of lysozyme, was analysed. P17 (sequence 1--27: Cys 6-Cys 127: 123--129) and P17t (sequence 1-Homoser 12: Cys 6-Cys 127: 123--129), which are known to be immunodominant antigenic determinants could induce helper T cells. When P17t was reduced and alkylated, one of the resultant peptides, P17tN (sequence 1-Homoser 12) could still induce helper T cells, but P17tC (sequence 123--129) could not. A synthetic peptide SP1-14 (sequence 1-Ala 6--14) also induced helper T cells. Thus the carrier determinant helping in antibody formation to the DNP residue at Lysine-33 may be localized in the region corresponding to the sequence 1--12 of lysozyme.
 ...
PMID:An immunological determinant for helper T cells at the N- and C-region of hen egg-white lysozyme. 617 Dec 47

The symbiosis between Rhizobium meliloti and Medicago sativa (Leguminosae) involves the interaction of lipochito-oligosaccharides (Nod factors) excreted by bacteria with specific proteins of the host plant. The cleavage of Nod factors can be used as an enzymic assay to identify novel hydrolytic enzymes. Here a soluble extract of 3-day-old roots was fractionated by anion exchange, affinity chromatography, gel filtration and native electrophoresis. Two acidic chitinases (pI 4.6-5.4), CHIT24 and CHIT36, designated in accordance with their molecular mass in kDa, were separated. CHIT24 cleaves all tested Nod factors to produce lipotrisaccharides with the preference NodRm-V(S)>NodRm-IV >NodRm-IV(S)>=NodRm-IV(Ac,S); it also hydrolyses colloidal 3H-chitin and has lysozyme activity. The kinetics of Nod factor degradation by CHIT24 depends on substrate structural parameters, namely the length of the oligosaccharide chain and sulphation (S) at the reducing end, but not much on acetylation (Ac) at the non-reducing end. The 25-residue N-terminal sequence of CHIT24 has no similarity with known chitinases or lysozymes, indicating that it is a novel type of hydrolase. CHIT36 also hydrolyses NodRm-V(S) into NodRm-III, but it is inactive towards NodRm-IV(S) and NodRm-IV(Ac,S) formed by R. meliloti. Finally, a 17 kDa protein, P17, was co-purified with CHIT24. It neither degrades Nod factors nor exhibits lysozyme activity and shows complete identity, at the 15-residue N-terminal sequence, with a class 10 pathogenesis-related protein, PR-10.
 ...
PMID:Purification and characterization of a novel chitinase-lysozyme, of another chitinase, both hydrolysing Rhizobium meliloti Nod factors, and of a pathogenesis-related protein from Medicago sativa roots. 960 Oct 60