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The innate immunity factor lactoferrin harbours two antimicrobial moieties, lactoferricin and lactoferrampin, situated in close proximity in the N1 domain of the molecule. Most likely they cooperate in many of the beneficial activities of lactoferrin. To investigate whether chimerization of both peptides forms a functional unit we designed a chimerical structure containing lactoferricin amino acids 17-30 and lactoferrampin amino acids 265-284. The bactericidal activity of this LFchimera was found to be drastically stronger than that of the constituent peptides, as was demonstrated by the need for lower dose, shorter incubation time and less ionic strength dependency. Likewise, strongly enhanced interaction with negatively charged model membranes was found for the LFchimera relative to the constituent peptides. Thus, chimerization of the two antimicrobial peptides resembling their structural orientation in the native molecule strikingly improves their biological activity.

Saliva is expected to be of significance for the perception of food stimuli in the mouth. Mixing the food with saliva, including breakdown and dilution, is considered to be of large importance for semi-solids as these products are masticated without chewing. It is known that there are large variations in composition of saliva originating from different glands and different subjects. In this study we investigated how variations in salivary characteristics affect sensory perception. Eighteen trained subjects participated in the study. Saliva was collected at rest and during three types of stimulation (odour, parafilm chewing and citric acid), and flow rates were determined. The collected saliva was analyzed for protein concentration, buffer capacity, mucin level and alpha-amylase activity. The salivary components measured in this study varied considerably among subjects, but also within subjects as a result of different means of stimulation. Variations in salivary components were correlated with sensory perception of a number of flavour, mouth feel and after feel attributes in the semi-solids mayonnaise and custard dessert. Total protein concentration and alpha-amylase activity were observed to correlate most strongly with texture perception.

Human saliva is secreted by the three pairs of major salivary glands (parotid, submandibular, and sublingual), and numerous minor ones, e.g. labial, buccal and (glosso)palatine glands. Using individually adapted collection devices, sublingual, submandibular, parotid and palatine secretions of five individuals were collected and analyzed. Electrophoretic analysis revealed that each type of saliva possesses characteristic features, despite interindividual variations. Parotid salivas are characterized by intensely staining amylase and proline-rich protein bands, but contain minute amounts of cystatins, lysozyme and the extra-parotid glycoprotein. Sublingual salivas are characterized by high concentrations of both types of salivary mucins, MG1 and MG2, and contain relatively high levels of lysozyme. Submandibular salivas contain highest concentration of salivary cystatin S. Palatine secretions contain high molecular weight mucins and a relatively high amylase concentration.

By using CsCl-density-gradient ultracentrifugation, two high-Mr mucin species were isolated from human whole saliva, having buoyant densities in 0.2 M-guanidinium chloride of approx. 1.56 g/ml (pool IA) and 1.48 g/ml (pool IIA). Analytical density-gradient centrifugation of submandibular, sublingual, labial and palatal saliva, followed by immunochemical analysis with anti-mucin monoclonal antibodies, indicated immunochemical and physicochemical similarities between the high-density mucins of pool IA and mucins from palatal salivary glands. Chemical analysis indicated that the putative palatal mucin was rich in sulphate, but poor in sialic acid. The lower-density mucins of pool IIA equated with the high-Mr mucins of submandibular-sublingual saliva, both immunochemically and physicochemically (buoyant density).

Using four Mabs with different specificities for salivary mucins, an ELISA has been developed in which human whole saliva, glandular salivas, salivary protein fractions and purified, high molecular-weight, mucin fractions (MG1) isolated from human submandibular and sublingual glandular tissues have been immunochemically analysed. All four Mabs reacted with MG1s. Three of them reacted with the purified, low molecular-weight salivary mucins (MG2). None was reactive with parotid saliva. MG1 preparations isolated from submandibular and sublingual glandular tissues of one and the same individual displayed different patterns of reactivity with these Mabs, indicating that they differ immunochemically. Analysis of the MG1s in salivas derived from individual salivary glands showed differences in immunochemical composition. These results indicate that the MG1 fraction in human whole saliva consists of several immunochemically different species.

Using the hybridoma technique, monoclonal antibodies (Mabs) have been produced against three different types of human salivary proteins: high molecular weight mucin, a 20 kD glycoprotein and a 14 kD protein, identified as a member of the cystatin family. The Mabs appeared to be highly specific to their antigen in Elisa and immunoblotting tests. The Mabs were of the IgG-1 (against 20 kD glycoprotein) and IgM (against 14 kD protein and mucin) type. For the 14 kD protein and the 20 kD glycoprotein it was demonstrated that they are present mainly in submandibular-sublingual saliva. None of the antigens studied could be localized distinctly in the human parotid gland. In the submandibular gland, the three proteins have a different pattern of localization. The mucins have been detected particularly in the apical part of the mucous acinar cells, the 20 kD glycoprotein mainly in the serous acinar cells and the 14 kD protein in both serous acinar cells and striated duct cells.

The isolation and chemical analysis of three human salivary proteins is reported. Using cation-exchange, FPLC anion-exchange chromatography and gel filtration, three human salivary proteins with affinity for hydroxyapatite were isolated, having molecular weights of 60 kD, 20 kD and 14 kD, respectively. The 60 kD protein was identified as albumin, and the 14 kD protein as a member of the cystatin family. Isoelectric focusing of the 14 kD protein revealed a single band, having an isoelectric point (pl) of 4.7. The third protein, not described yet, is appearing as a 20 kD doublet on SDS-PAGE. Isoelectric focusing resolved the 20 kD protein into four bands having pl's of 4.8, 5.0, 5.2 and 5.4, respectively. All bands were recognized by monoclonal antibodies to the 20 kD protein indicating that these four protein bands share the same epitope. The 20 kD protein is a glycoprotein with a carbohydrate content of 13% and a molar ratio of Fuc: Man: Gal: GlcNAc: NeuAc = 3.4:2.6:2.9:4.0:0.4. All three proteins bind strongly to a hydroxyapatite-based HPHT column at pH 6.0. With increasing pH, the binding diminished, especially of the 14 kD protein.