Jacqueline Jollès

What's new in lysozyme research?

SummaryThe present review is focused on the main achievements realized in the lysozyme research field since the meeting held in 1972 to commemorate the fiftieth anniversary of the discovery of this enzyme. Despite of extensive structural, physico-chemical, crystallographic, genetic, immunological and evolutionary studies devoted to lysozymes, their biological role is still not exactly known.

La structure chimique du lysozyme de blanc d'oeuf de poule: étude détaillée☆

All the details concerning the establishment of the formula of the chemical structure of hens egg-white lysozyme (N-acetylmuramide glycanohydrolase, EC 3.2.1.17) (which the authors had briefly indicated in 1961) are reported in the present study. The 18 tryptic units obtained from reduced lysozyme by chromatography on Dowex-1 X2 have beeb joined in the right order thanks to the chymotryptic units containing a basic amino acid and in two instances thanks to the peptic units. The protein is formed by a single polypeptide chain of 129 amino acid residues folded by the 4 bridges of the cystine residues; one of them has already been determined. Some considerations are made on the relations existing between chemical structure and biological activity.

cDNA and amino acid sequences of rainbow trout (Oncorhynchus mykiss) lysozymes and their implications for the evolution of lysozyme and lactalbumin.

SummaryThe complete 129-amino-acid sequences of two rainbow trout lysozymes (I and II) isolated from kidney were established using protein chemistry microtechniques. The two sequences differ only at position 86, I having aspartic acid and II having alanine. A cDNA clone coding for rainbow trout lysozyme was isolated from a cDNA library made from liver mRNA. Sequencing of the cloned cDNA insert, which was 1 kb in length, revealed a 432-bp open reading frame encoding an amino-terminal peptide of 15 amino acids and a mature enzyme of 129 amino acids identical in sequence to II. Forms I and II from kidney and liver were also analyzed using enzymatic amplification via PCR and direct sequencing; both organs contain mRNA encoding the two lysozymes. Evolutionary trees relating DNA sequences coding for lysozymesc and α-lactalbumins provide evidence that the gene duplication giving rise to conventional vertebrate lysozymesc and to lactalbumin preceded the divergence of fishes and tetrapods about 400 Myr ago. Evolutionary analysis also suggests that amino acid replacements may have accumulated more slowly on the lineage leading to fish lysozyme than on those leading to mammal and bird lysozymes.

Amino acid composition of κ-casein and terminal amino acids of κ- and para-κ-casein☆

Abstract The amino acid composition of κ-casein is reported. Carboxypeptidase liberates Ser, Thr, Ala and Val from κ-casein, Leu and Phe from para-κ-casein. These Leu and Phe residues may be involved in the linkage (probably an ester linkage) split by rennin during its action on κ-casein.

Insect lysozymes from three species of lepidoptera: Their structural relatedness to the c (chicken) type lysozyme

SummarySequence studies of the N-terminal halves of the lysozymes isolated fromBombyx mori, Galleria mellonella andSpodoptera littoralis (Lepidoptera) allow us to classify these enzymes among the c (chicken) type lysozymes.

Purification and N-terminal amino-acid sequence of a basic lysozyme from Parthenocissus quinquifolia cultured in vitro

Abstract Parthenocissus quinquifolia cells cultured in vitro produced a lysozyme with a high chitinase activity. The lysozyme was purified from the supernatant of a suspension culture. It was characterized and its N-terminal amino-acid sequence established. A strong structural similarity between this enzyme and the major lysozyme purified from Hevea brasiliensis latex was observed. An enzyme test for the classification of a plant enzyme among lysozymes or chitinases is also described.

Episodic Evolution in the Stomach Lysozymes of Ruminants

SummaryBy sequencing lysozymesc from deer and pig stomachs and comparing them to the known amino acid sequences of other lysozymesc, it was possible to examine the rate of sequence change during and after the period in which this enzyme acquired a new function. Evolutionary tree analysis suggests that the rate went up while lysozyme was being recruited to function as a digestive enzyme in the stomach of early ruminants. Later, presumably after lysozyme was well adapted for functioning in the new environment, which contains acid, pepsin, and fermentation products, the rate of amino acid replacement became subnormal.

Characterization and localization of an iron-binding 18-kDa glycopeptide isolated from the N-terminal half of humanlactotransferrin

Mild treatment of iron-saturated human lactotransferrin by trypsin at pH 8.2 cleaves the molecule into a N-tryptic (Mr ≈ 30 000) and a C-tryptic (Mr ≈ 50 000) fragment, which have been isolated. Each of them carries a glycan moiety and keeps the property to bind reversibly one Fe3+. The N-tryptic fragment has been submitted to a second tryptic digestion which led to an iron-binding glycopeptide fragment with a molecular weight of about 18 500. This fragment, the smallest iron-binding peptide isolated up to now from a transferrin, includes the ND2 domain of human lactotransferrin.

Complete amino acid sequence of human vitamin D-binding protein (group-specific component): evidence of a three-fold internal homology as in serum albumin and α-fetoprotein

Abstract The complete amino acid sequence (458 amino acid residues) of human group-specific component 2 (Gc2) protein was determined. Computer analyses established a three-fold internal homology of Gc2 protein as well as an extensive homology between the overall structures of Gc2 protein, human serum albumin and human α-fetoprotein.

Amino acid sequence and immunological properties of chachalaca egg white lysozyme

SummaryThe amino acid sequence of lysozyme c from chachalaca egg white was determined. Like other bird lysozymes c, that of the chachalaca has 129 amino acid residues. It differs from other avian lysozymes c by 27 to 31 amino acid substitutions as well as by being devoid of phenylalanine. It contains substitutions at 9 positions which are invariant in the other 7 bird lysozymes of known sequence. Although the chachalaca is classified zoologically in the order Galliformes, which includes chickens and other pheasant-like birds, its lysozyme differs more from those of pheasant-like birds than do the lysozymes c of ducks. Phylogenetic analysis of the sequence comparisons confirms that the lineage leading to chachalaca lysozyme c separated from that leading to other galliform lysozymes c before the duck lysozyme c lineage did. This indicates a contrast between protein evolution and evolution at the organismal level. Immunological comparison of chachalacalysozyme c with other lysozymes of known sequence provides further support for the proposal that immunological cross-reactivity is strongly dependent on degree of sequence resemblance among bird lysozymes.