Lactoperoxidase (EC 1.11.1.7) catalysed the oxidation of NADH by hydrogen peroxide in the presence of either thiocyanate, iodide or bromide. In the presence of thiocyanate, net oxidation of thiocyanate occurred simultaneously with the oxidation of NADH, but in the presence of iodide or bromide, only the oxidation of NADH occurred to a significant extent. In the presence of thiocyanate or bromid...

The topology of the human erythrocyte membrane anion-transport protein (band 3) has been investigated by isolation and peptide 'mapping' of the major and minor fragments derived from proteolytic cleavage of the lactoperoxidase 125I-labelled protein in erythrocytes and erythrocyte membranes. The content, in each fragment, of lactoperoxidase 125I-labelled sites (which have a known location in the...

Myeloperoxidase, eosinophil peroxidase and lactoperoxidase are heme-containing oxidoreductases, which undergo a series of redox reactions. Though sharing functional and structural homology, reflecting their phylogenetic origin, differences are observed regarding their spectral features, substrate specificities, redox properties and kinetics of interconversion of the relevant redox intermediates...

Innate Airway Defenses Airway secretions provide critical elements of the innate, i.e., nonantigen specific, defense of the respiratory tract against inhaled microorganisms. Such a system is required to maintain sterility of the lungs in the settings of constant exposure to inhaled debris and potential pathogens and of their proximity to the oral and nasopharyngeal cavities, both of which are c...

The turnover of plasma membrane proteins in primary rat hepatocyte cultures was examined by following the loss of polypeptides labeled in situ by lactoperoxidase-catalyzed iodination using 125I and 131I. Most plasma membrane proteins had similar rates of degradation, having a half-life of approximately 85 h. By in situ labeling via lactoperoxidase-catalyzed iodination, as well as metabolically ...

Ribosomal proteins L7 and L12 are involved in the initiation, elongation and termination of polypeptide synthesis [l-6]. These acidic proteins do not function independently, but act in concert with the ribosome to perform the above steps. These observations suggest that L7 and L12 are necessary to maintain the conformational integrity of the ribosome, and that loss of ribosomal activity followi...

Airway mucus is a complex mixture of secretory products that provides a multifaceted defense against pulmonary infection. Mucus contains antimicrobial peptides (e.g., defensins) and enzymes (e.g., lysozyme) although the contribution of these to airway sterility has not been tested in vivo. We have previously shown that an enzymatically active, heme-containing peroxidase comprises 1% of the solu...

A novel mechanism of protein attachment to cell membranes involving the covalent linkage of the protein through an oligosaccharide to phosphatidylinositol has recently been defined. Many proteins that are anchored to the cell membrane by this mechanism can be released by treatment with phosphatidylinositol-specific phospholipase C (PI-PLC). Monoclonal antibodies are useful as probes in the stud...

The endogenous dopamine-derived neurotoxin salsolinol was found to decrease survival in the dopaminergic neuronal cell line RCSN-3, derived from adult rat substantia nigra in a concentration-dependent manner (208 microM salsolinol induced a 50% survival decrease). Incubation of RCSN-3 cells with 100 micro;M dicoumarol and salsolinol significantly decreased cell survival by 2.5-fold (P < 0.001),...

Line 1, a spontaneous alveolar carcinoma from a BALB/c mouse, is highly metastatic and weakly antigenic in the syn geneic host. Sera and enriched antibody preparations were made specific for line 1 cells by in vitro and in vivo absorptions. By lactoperoxidase-catalyzed radioiodination of cell surface protein followed by precipitation with specific antibodies, a protein with a molecular weight o...