Studies on cell-clearing activity in alpha-lactalbumin. Effects of calcium removal on activity and conformation.

Effects of calcium removal on the cell-clearing activity of alpha-lactalbumin (alpha-LA) and concomitant changes in conformational structure have been investigated as part of a continuing study of the activity found earlier [McKenzie, H.A. & White, F.H., Jr. (1987) Biochem. Int. 14, 347]. This activity is similar to that of lysozyme, whereby lysis of the bacterial cell wall is catalyzed. However, the specific activity of alpha-LA is on the order of 10(-6) that of lysozyme. Under conditions where activities of apo and native alpha-LA were approximately linear functions of the protein concentration, the maximal ratio of apo to native activity was 5.7:1, determined by comparison of second order velocity constants. The CD spectrum of apo alpha-LA is intermediate between that of the A state and the native protein. By NMR, the conformation of apo alpha-LA is similar to, but distinctly different from, that of the native protein. The apo form did not revert completely to the native state when Ca(II) was resupplied, consistent with a role for this cation in folding. It is suggested that the activity increase may result from a diminished constriction of the "cleft" region in alpha-LA.     

Evidence for a novel enzymatic mechanism of neural crest cell migration on extracellular glycoconjugate matrices

Migrating embryonic cells have high levels of cell surface galactosyltransferase (GalTase) activity. It has been proposed that GalTase participates during migration by recognizing and binding to terminal N-acetylglucosamine (GlcNAc) residues on glycoconjugates within the extracellular matrix (Shur, B. D., 1982, Dev. Biol. 91:149-162). We tested this hypothesis using migrating neural crest cells as an in vitro model system. Cell surface GalTase activity was perturbed using three independent sets of reagents, and the effects on cell migration were analyzed by time-lapse microphotography. The GalTase modifier protein, alpha-lactalbumin (alpha-LA), was used to inhibit surface GalTase binding to terminal GlcNAc residues in the underlying substrate. alpha-LA inhibited neural crest cell migration on basal lamina-like matrices in a dose-dependent manner, while under identical conditions, alpha-LA had no effect on cell migration on fibronectin. Control proteins, such as lysozyme (structurally homologous to alpha-LA) and bovine serum albumin, did not effect migration on either matrix. Second, the addition of competitive GalTase substrates significantly inhibited neural crest cell migration on basal lamina-like matrices, but as above, had no effect on migration on fibronectin. Comparable concentrations of inappropriate sugars also had no effect on cell migration. Third, addition of the GalTase catalytic substrate, UDPgalactose, produced a dose-dependent increase in the rate of cell migration. Under identical conditions, the inappropriate sugar nucleotide, UDPglucose, had no effect. Quantitative enzyme assays confirmed the presence of GalTase substrates in basal lamina matrices, their absence in fibronectin matrices, and the ability of alpha-LA to inhibit GalTase activity towards basal lamina substrates. Laminin was found to be a principle GalTase substrate in the basal lamina, and when tested in vitro, alpha-LA inhibited cell migration on laminin. Together, these experiments show that neural crest cells have at least two distinct mechanisms for interacting with the substrate during migration, one that is fibronectin-dependent and one that uses GalTase recognition of basal lamina glycoconjugates.     

Different binding of human interferon alpha 1 and alpha 2 to common receptors on human and bovine cells. Studies with recombination interferons produced in Escherichia coli

Minicells from Escherichia coli DS410 harboring cDNA for human interferon (IFN) alpha 1 or alpha 2 were metabolically labeled with [3H]leucine and the radioactive IFN was purified to homogeneity by immune precipitation with anti-IFN-alpha serum. These preparations of radioactive IFN-alpha 1 and -alpha 2 were used to study the binding on two human (FL and Daudi) and one bovine (MDBK) cell lines. IFN-alpha 2 specifically bound well to both human and bovine cells, while IFN-alpha 1 bound very poorly to human cells but well to bovine cells. Specific binding of radioactive IFN-alpha 2 to these cell lines was completely inhibited by not only nonradioactive IFN-alpha 2 but also IFN-alpha 1, and binding of IFN-alpha 1 to bovine cell was also competed by IFN-alpha 2 as well as IFN-alpha 1, indicating that the receptors for both IFNs are identical. However, 50-100-fold (on human cells) or 4-fold (on bovine cell) more nonradioactive IFN-alpha 1 than -alpha 2 was required to inhibit the binding of radioactive IFN-alpha 2 to the receptors. Scatchard analysis showed that IFN-alpha 1 and -alpha 2 bind to the receptors on human cells with an apparent Kd of greater than 6 X 10(-10) and 3 X 10(-11) M, respectively, while on bovine cells with a Kd of 4.2 X 10(-11) and 1.6 X 10(-11) M, respectively. These results show that the different target cell specificity of IFN-alpha 1 and -alpha 2 in regard to antiviral activity (Streuli, M., Hall, A., Boll, W., Stewart, W. E., II, Nagata, S., and Weissmann, C. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 2848-2852) is due to the different binding activity of IFN-alpha molecules to their common receptors.     

Apo alpha-lactalbumin and lysozyme are colocalized in their subsequently formed spherical supramolecular assembly

We have reported previously that the calcium-depleted form of bovine alpha-lactalbumin (apo alpha-LA) interacts with hen egg-white lysozyme (LYS) to form spherical supramolecular structures. These supramolecular structures contain an equimolar ratio of the two proteins. We further explore here the organization of these structures. The spherical morphology and size of the assembled LYS/apo alpha-LA supramolecular structures were demonstrated using confocal scanning laser microscopy and scanning electron microscopy. From confocal scanning laser microscopy experiments with labelled proteins, it was found that LYS and apo alpha-LA were perfectly colocalized and homogeneously distributed throughout the entire three-dimensional structure of the microspheres formed. The spatial colocalization of the two proteins was also confirmed by the occurrence of a fluorescence resonance energy transfer phenomenon between labelled apo alpha-LA and labelled LYS. Polarized light microscopy analysis revealed that the microspheres formed differ from spherulites, a higher order semicrystalline structure. As the molecular mechanism initiating the formation of these microspheres is still unknown, we discuss the potential involvement of a LYS/apo alpha-LA heterodimer as a starting block for such a supramolecular assembly.     

Zinc binding in bovine alpha-lactalbumin: sequence homology may not be a predictor of subtle functional features

alpha-Lactalbumin (alpha-LA), a calcium-binding protein, also possesses zinc-binding sites comprising a single strong site and several weaker secondary sites. The only site found by X-ray crystallography (Ren et. al., J. Biol. Chem. 1993;268:19292) was Glu 49 of human alpha-LA, but zinc binding had never been measured in solution for human alpha-LA. This residue was genetically substituted by Ala in bovine alpha-LA and the metal-binding properties of the resulting desMetE49A protein were compared with those for native alpha-LA by fluorescence methods. Surprisingly, desMetE49A alpha-LA and the native bovine protein had similar affinities for both Zn(2+) and Ca(2+). Genetic substitution of other possible candidates for Zn(2+) chelating residues, which included Glu 25, did not alter the affinity of bovine alpha-LA to Zn2+; however, substitution of Glu 1 by Met resulted in the disappearance of strong Zn(2+) binding. A proposed site involves Glu 1, Glu 7, Asp 11, and Asp 37, which would participate in strong Zn(2+) binding based on their propinquity to Glu 1. Human alpha-LA, which has a Lys at position 1 rather than Glu, binds zinc with a reduced affinity compared with native bovine alpha-LA, suggesting that the site identified from the X-ray structure did not correspond to strong zinc binding in solution.     

Comparison of oxidative metabolism in vitro in endothelial cells from different species and vessels

Oxygen consumption was compared in confluent cultures of endothelial cells from human umbilical cord veins, rat pulmonary arteries, and bovine aortas. A microrespirometric method utilizing oxygenated hemoglobin as oxygen supply and indicator of respiration was used. Respiratory rate was equal in human and murine cells (2.0 X 10(-6) and 2.2 X 10(-6) microliters O2/cell/hour respectively), compared on a cell-to-cell basis, while respiratory rate of the bovine endothelium was significantly lower (0.4 X 10(-6) microliters O2/cell/hour) (P less than .001).     

Purification of camel milk lysozyme and its lytic effect on Escherichia coli and Micrococcus lysodeikticus

1. Camel milk lysozyme was purified using heparin-Sepharose 4B, Sephadex G-75 and hydroxyapatite chromatography. By this procedure lysozyme was separated from lactoferrin and a low molecular weight protein. 2. The lytic effect of camel milk lysozyme was assayed using Escherichia coli and Micrococcus lysodeikticus and its activity was compared with that of lysozyme from human milk and egg white. 3. The specific activity of camel milk lysozyme was found to be lower than that of lysozyme from human milk or from egg white. 4. Camel milk lactoferrin did not show a lytic effect on bacteria, while the low molecular weight protein showed lytic activity.     

Purification, amino acid sequence, and some properties of rabbit kidney lysozyme

The lysozyme (rabbit kidney lysozyme) from the homogenate of rabbit kidney (Japanese white) was purified by repeated cation-exchange chromatography on Bio-Rex 70. The amino acid sequence was determined by automated gas-phase Edman degradation of the peptides obtained from the digestion of reduced and S-carboxymethylated rabbit lysozyme with Achromobacter protease I (lysyl endopeptidase). The sequence thus determined was KIYERCELARTLKKLGLDGYKGVSLANWMCLAKWESSYNTRATNYNPGDKSTDYGIFQ INSRYWCNDGKTPRAVNACHIPCSDLLKDDITQAVACAKRVVSDPQGIRAWVAWRNHCQ NQDLTPYIRGCGV, indicating 25 amino acid substitutions from human lysozyme. The lytic activity of rabbit lysozyme against Micrococcus lysodeikticus at pH 7, ionic strength of 0.1, and 30 degrees C was found to be 190 and 60% of those of hen and human lysozymes, respectively. The lytic activity-pH profile of rabbit lysozyme was slightly different from those of hen and human lysozymes. While hen and human lysozymes had wide optimum activities at around pH 5.5-8.5, the optimum activity of rabbit lysozyme was at around pH 5.5-7.0. The high proline content (five residues per molecule compared with two prolines per molecule in hen or human lysozyme) is one of the interesting features of rabbit lysozyme. The transition temperatures for the unfolding of rabbit, human, and hen lysozymes in 3 M guanidine hydrochloride at pH 5.5 were 51.2, 45.5, and 45.4 degrees C, respectively, indicating that rabbit lysozyme is stabler than the other two lysozymes. The high proline content may be responsible for the increased stability of rabbit lysozyme.     

Stability of the molten globule state of a domain-exchanged chimeric protein between human and bovine alpha-lactalbumins

A domain-exchanged chimeric alpha-lactalbumin (alpha-LA), which consisted of the alpha-domain of human alpha-LA and the beta-domain of bovine alpha-LA, was constructed. Like native alpha-LA, the chimeric protein was in a molten globule state in the absence of Ca(2+) at neutral pH and low salt concentration. The stability of the molten globule state of the constructed chimeric protein was identical to that of the recombinant human protein and was higher than that of the recombinant bovine protein. The stability of the molten globule state of alpha-LA is defined by the stability of the alpha-domain.     

Determination of lysozyme activity at low levels with emphasis on the milk enzyme

A method is described for the determination of lysozyme (muramidase) activity, whereby sensitivity is maximized by incubation of the reaction mixture (sample, buffer, and substrate (Micrococcus luteus] over an extended period. This approach is made feasible by exploiting our observation that the lytic reaction follows simple kinetic order during this time (e.g., 700 min for bovine lysozyme and 960 min for the eggwhite enzyme at low concentrations). After this period, the reaction rates diminish, indicating biphasic behavior, and eventually become negligible. The kinetic order may vary with both the type of lysozyme and the buffer system used. The limit of detection for bovine milk lysozyme is 100 pg/ml reaction mixture, equivalent to 6 ng/ml milk, for a 50-microliters sample (with reference to hen eggwhite lysozyme). With these limits, the method has proven valuable in our comparative studies, particularly for low levels of activity in bovine milk, but also in secretions and tissue extracts from various other eutherian, metatherian, and prototherian mammals. The method may also be applied to investigation of structure and function in modified forms of the enzyme.     

Some properties of the lysozymes in serum and colostrum from cows with high and low lytic power against Micrococcus lysodeikticus

Previous work has uncovered a dominant gene for high bacteriolytic activity of bovine serum against the test bacterium Micrococcus lysodeikticus. This major gene effect is also fully expressed in colostrum. In the present study the lytic power of serum and colostral whey from high and low level cows was subjected to a degree of characterization. It was found that the enzyme activities studied exhibited properties in accordance with those defined for a lysozyme (EC 3.2.1.17), i.e. (1) lysis of a suspension of M. lysodeikticus, (2) basic protein (pI = 10.0 and pI = 10.3 for bovine serum lysozyme (BSL) and bovine colostrum lysozyme (BCL), respectively), (3) molecular weight (MW) approximately 16 000 for both BSL and BCL, (4) liberation of free reducing sugars during action on cell wall peptidoglycan (the kinetics of BSL and BCL differed strongly), and (5) fairly heat stable, especially at acidic pH and relative labile at alkaline pH (BCL was far more sensitive to heating at alkaline pH than was BSL). The dramatic differences in activity between high and low level animals might be due to a major genetic mechanism influencing the amount of, or the activity of, circulating enzyme molecules, rather than a structural gene coding for a certain enzyme with a particular specific activity. This is also supported by the high correlation between the lytic capacity of BSL and BCL in spite of the different properties of these lysozymes (i.e. in respect of pI, enzyme kinetics and heat stability) reported in the present study.     

Engineering of human lysozyme as a polyelectrolyte by the alteration of molecular surface charge

The surface positive charges of human lysozyme were either increased or decreased to alter the electrostatic interaction between enzyme and substrate in the lytic action of human lysozyme using site-directed mutagenesis. The amino acid substitutions accompanying either the addition or the removal of two units of positive charge have shifted the optimal ionic strength (NaCl concentration in 10 mM Mes buffer, pH 6.2) for the lysis of Micrococcus lysodeikticus cell from 0.04 M to 0.1 M and from 0.04 M to 0.02 M respectively. In addition to the change in ionic strength-activity profile, the pH-activity profile and the effect of a polycationic electrolyte, poly-L-Lys-HCl, on the lytic activity were significantly changed. Owing to the shifts in both ionic strength profiles and pH profiles the Arg74/Arg126 mutant has become a better catalyst than wild-type enzyme under the conditions of high ionic strength and high pH, and the Gln41/Ser101 mutant has become a better catalyst under the conditions of low ionic strength and low pH.     

Mutating aspartate in the calcium-binding site of alpha-lactalbumin: effects on the protein stability and cation binding.

The residue Asp87, which is in the calcium-binding loop of bovine alpha-lactalbumin (alpha-LA) and provides a side-chain carboxylate oxygen for ligand Ca(II) co-ordination, was substituted by either alanine or asparagine. The physical properties and calcium-binding affinities were monitored by intrinsic fluorescence and circular dichroism spectroscopy. D87A alpha-LA displayed a total loss of rigid tertiary structure, a dramatic loss in secondary structure and negligible calcium affinity [Anderson et al. (1997) Biochemistry, 36, 11648-11654]. On the contrary, D87N alpha-LA displayed native-like secondary structure with a somewhat de-stabilized tertiary structure. When the well-documented N-terminal methionine was enzymatically removed from D87N alpha-LA [Veprintsev et al. (1999) PROTEINS: Struct. Funct. Genet., 37, 65-72], the structure appeared to more closely resemble native alpha-LA. Remarkably, the thermal transition mid-temperature of apo-desMetD87N alpha-LA was approximately 31 degrees C versus native apo- alpha-LA (approximately 25 degrees C), probably due to negative charge 'compensation' in the calcium co-ordination site. On the other hand, the transition mid-temperature of Ca(II)-bound desMetD87N alpha-LA was approximately 57 degrees C versus native alpha-LA (approximately 66 degrees C), which was related to a decreased Ca(II) affinity (K = approximately 2.1 x 10(5) versus approximately 1.7 x 10(7)/M at 40 degrees C, respectively). These results reaffirm that alanine substitution in site specific mutagenesis is not always a prudent choice. Substitutions must be conservative with only minimal changes in functional groups and side-chain volume.     

Alpha-lipoic acid induces apoptosis in hepatoma cells via the PTEN/Akt pathway

We report here that alpha-lipoic acid (alpha-LA), a naturally-occurring antioxidant, scavenges reactive oxygen species (ROS) followed by an increase in apoptosis of human hepatoma cells. Apoptosis induced by alpha-LA was dependent upon the activation of the caspase cascade and the mitochondrial death pathway. alpha-LA induced increases in caspase-9 and caspase-3 but had no significant effect on caspase-8 activity. Apoptosis induced by alpha-LA was found to be mediated through the tensin homologue deleted on chromosome 10 (PTEN)/Akt pathway. Prior to cell apoptosis, PTEN was activated and its downstream target Akt was inhibited. Our findings indicate that increasing ROS scavenging could be a therapeutic strategy to treat cancer.     

Calcium-43 NMR studies of calcium-binding lysozymes and alpha-lactalbumins.

The calcium-binding properties of equine and pigeon lysozyme as well as those of bovine and human alpha-lactalbumin were investigated by 43Ca NMR spectroscopy. All proteins were found to contain one high-affinity calcium-binding site. The chemical shifts, line widths, relaxation times (T1 and T2), and quadrupole coupling constants for the respective 43Ca NMR signals were quite similar; this is indicative of a high degree of homology between the strong calcium-binding sites of these four proteins. The measured chemical shifts (delta approximately -3 to -7 ppm) and quadrupole coupling constants (chi approximately 0.7-0.8 MHz) are quite distinct from those observed for typical EF-hand calcium-binding proteins, suggesting a different geometry for the calcium-binding loops. The correlation times for bound calcium ions in these proteins were on the order of 4-8 ns, indicating that the flexibilities of these binding sites are limited. The apparent pKa values for the high-affinity sites ranged from 3.4 to 4.7, confirming the participation of carboxylate-containing residues in the coordination of the calcium ion. Competition experiments with EDTA showed that the affinities of these proteins for calcium follow the series bovine alpha-lactalbumin approximately human alpha-lactalbumin greater than pigeon lysozyme greater than equine lysozyme (KD approximately 5 x 10(-8) to 10(-6) M). Evidence for the existence of a second weak calcium-binding site (KD = 3 x 10(-3) M) was obtained for bovine alpha-lactalbumin, but not for the other proteins studied.(ABSTRACT TRUNCATED AT 250 WORDS)     

Production of human lysozyme in biofilm reactor and optimization of growth parameters of Kluyveromyces lactis K7

Lysozyme (1,4-β-N-acetylmuramidase) is a lytic enzyme, which degrades the bacterial cell wall. Lysozyme has been of interest in medicine, cosmetics, and food industries because of its anti-bactericidal effect. Kluyveromyces lactis K7 is a genetically modified organism that expresses human lysozyme. There is a need to improve the human lysozyme production by K. lactis K7 to make the human lysozyme more affordable. Biofilm reactor provides high biomass by including a solid support, which microorganisms grow around and within. Therefore, the aim of this study was to produce the human lysozyme in biofilm reactor and optimize the growth conditions of K. lactis K7 for the human lysozyme production in biofilm reactor with plastic composite support (PCS). The PCS, which includes polypropylene, soybean hull, soybean flour, bovine albumin, and salts, was selected based on biofilm formation on PCS (CFU/g), human lysozyme production (U/ml), and absorption of lysozyme inside the support. To find the optimum combination of growth parameters, a three-factor Box–Behnken design of response surface method was used. The results suggested that the optimum conditions for biomass and lysozyme productions were different (27 °C, pH 6, 1.33 vvm for biomass production; 25 °C, pH 4, no aeration for lysozyme production). Then, different pH and aeration shift strategies were tested to increase the biomass at the first step and then secrete the lysozyme after the shift. As a result, the lysozyme production amount (141 U/ml) at 25 °C without pH and aeration control was significantly higher than the lysozyme amount at evaluated pH and aeration shift conditions (p?<?0.05).     

Enzymatic lysis of staphylococcal cells and isolation of cell walls

Procedures for lyzing staphylococcal cells with the use of ultrasound, lysozyme and a lytic enzyme complex of Actinomyces recifensis var. lyticus, 2435 were compared. The lysis level was estimated by two parameters: lower optical density and protein yield percentage. It was found that ultrasound provided rather high levels of cell destruction reaching 60-68 per cent. The use of lysozyme enabled to destroy 16 per cent of the cells. The enzyme complex of strain 2435 showed high lytic activity with respect to the tested culture. For destroying dense staphylococcal suspensions it appeared necessary to study the effect of preliminary treatment of the cells with various chemical substances on their liability to the effect of the enzyme complex. It was demonstrated that treatment of the cells with 0.01-0.1 M cystein HCl solutions, 0.01-0.02 M sodium dodecylsulfate solutions or 0.05-0.5 M sodium hydroxide solutions increased 2.6-4.7-fold the cell liability to enzymatic hydrolysis. The studies enabled to develop conditions providing complete lysis of 10-percent staphylococcal cell suspension within 5 to 15 minutes under the effect of the lytic enzyme complex of strain 2435. A procedure for isolating cell walls was developed.     

Protein degradation by human intestinal bacteria

Analysis of human gut contents showed that substantial quantities of soluble protein, ammonia and branched chain volatile fatty acids occurred throughout the large intestine [0.1-24.4 g (kg contents)-1, 7.7-66.0 mmol (kg contents)-1 and 1.5-11.1 mmol (kg contents)-1 respectively]. The presence of these metabolites suggested that substantial proteolysis was occurring. In vitro studies showed that casein and bovine serum albumin were partly degraded in slurries of human faeces over a 96 h incubation period, to produce TCA-soluble peptides, ammonia and volatile fatty acids. Proteolytic activity detected in the stools of five individuals ranged from 3.5 to 19.8 mg azocasein hydrolysed h-1 (g faecal material)-1. Washed cell and washed particulate faecal fractions accounted for 24-67% of total activity. The predominant proteolytic bacteria in the faecal samples examined were identified as Bacteroides spp. [1.0 X 10(11)-1.3 X 10(12) (g dry wt faeces)-1] and Propionibacterium spp. [1.2 X 10(8)-1.0 X 10(10) (g dry wt faeces)-1]. Other proteolytic bacteria which occurred in lesser numbers were identified as belonging to the genera Streptococcus, Clostridium, Bacillus and Staphylococcus. These results demonstrate that the gut microflora could potentially play a major role in proteolysis in the human colon.     

Transfer of the human X chromosome to human--Chinese hamster cell hybrids via isolated HeLa metaphase chromosomes.

Evidence is presented for the uptake of the human X chromosome by human-Chinese hamster cell hybrids which lack H P R T activity, following incubation with isolated human HeLa S3 chromosomes. Sixteen independent clonal cell lines were isolated in H A T medium, all of which contained a human X chromosome as determined by trypsin-Giemsa staining. The frequency of H A T-resistant clones was 32 x 10(-6) when 10(7) cells were incubated with 10(8) HeLa chromosomes. Potential reversion of the hybrid cells in H A T medium was less than 5 x 10(-7). The 16 isolated cell lines all contained activity of the human X-linked marker enzymes H P R T, P G K,alpha-Gal A, and G6PD, as determined by electrophoresis. The phenotype of G6PD was G6PD A, corresponding to G6PD A in HeLa cells. The human parental cells used in the fusion to form the hybrids had the G6PD B phenotype. The recipient cells gave no evidence of containing human X chromosomes. These results indicate that incorporation and expression of HeLa X chromosomes is accomplished in human-Chinese hamster hybrids which lack a human X chromosome.     

Human ovarian cancer, lymphoma spleen, and bovine milk GlcNAc:beta1,4Gal/GalNAc transferases: two molecular species in ovarian tumor and induction of GalNAcbeta1,4Glc synthesis by alpha-lactalbumin

Affinity Gel-UDP was utilized to purify GlcNAc:beta1,4Gal/GalNAc transferases (Ts) from human lymphoma spleen, ovarian tumor, and ovarian cancer sera. Mn(2+) was found to be an absolute requirement for activity. Two molecular species containing both beta1,4Gal/GalNAc-T activities were discernible when the purified ovarian tumor microsomal enzyme was subjected to Sephacryl S-100 HR column chromatography as well as native polyacylamide gel-electrophoresis. Acceptor specificity studies of the affinity-purified lymphoma spleen and ovarian tumor microsomal enzymes and the conventionally purified, as well as the cloned, bovine milk GlcNAc:beta1,4Gal-Ts using a number of synthetic acceptors showed that the beta(1,6)-linked GlcNAc moiety to alpha-GalNAc was the most efficient acceptor. As compared to the purified milk enzyme, the recombinant form exhibited sixfold GlcNAc:beta1,4 GalNAc-T activity and up to eightfold GlcNAc6SO3beta-:beta1,4Gal-T activity. Further, the recombinant enzyme catalyzed the transfer of GalNAc to the terminal beta-linked GlcNAc6SO3 moiety. Alpha-lactalbumin (alpha-LA) inhibited up to 85%, the transfer of Gal to the GlcNAc moiety linked either to Man or GlcNAc. On the contrary, alpha-LA had no significant influence on the transfer of GalNAc to the above acceptors. alpha-LA had no appreciable effect on the recombinant enzyme, except for the transfer of Gal or GalNAc to Glc. Both alpha- and beta-glucosides, as well as alpha-N-acetylglucosaminide, did not serve as acceptors.