α-La f(1-5) [id=ALA0003]

Producer Organism : Native Protein : Production Method :
Cow α-lactalbumin Enzymatic hydrolysis and Purification with LC method/Synthetic
Activity : Antibacterial
Target Organisms :

Gram-positive: Active against Bacillus subtilis BGA, Micrococcus luteus ATCC 4698, Staphylococcus epidermidis ATCC 12228, Staphylococcus lentus, Streptococcus zooepidemicus.

Gram-negative: Active against Bordetella bronchiseptica.

NOTE: No activity against Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 13883, Serratia marcescens ATCC 8100, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, Candida albicans ATCC 2091 .

Description :
Production method: Trypsin hydrolysis and purification with LC method/Synthetic.

Length : 5 Mass (Da): 618.01 Common Amino Acids : QTKLE
Isolectric Point : 6.41 Net Charge : Absent Amino Acids : ACDFGHIMNPRSVWY
Basic Residues : 1 Acidic Residues : 1 Hydrophobic Residues : 1
Polar Residues : 1 Boman Index : -15.55 Hydropathy Index : -1.56
Aliphatic Index : 78 Instability Index : 0 Extinction Coefficient :
Absorbance 280nm : 0

Wheel representation

Hydrophobicity plot

Red solid plot : values according to the hydrophobicity scale of Kyte and Doolittle (reference paper).
Yellow dashed plot : Experimentally determined hydrophobicity scale for proteins at membrane interfaces(reference paper).
Green dotted-dashed plot : prediction of transmembrane helices (reference paper). In this scale (unlike the others), more negative values reflect greater hydrophobicity.

Citation: 1

Isolation and identification of three bactericidal domains in the bovine alpha-lactalbumin molecule

Cited Entries: ALA0003, ALA0004, ALA0005, ALA0006

Authors:Pellegrini, A., Thomas, U., Bramaz, N., Hunziker, P., von Fellenberg, R.
Journal: Biochimica et Biophysica Acta (BBA) - General Subjects 1999, 1426(3).
CrossRef External Link
Abstract: Proteolytic digestion of alpha-lactalbumin by pepsin, trypsin and chymotrypsin yielded three polypeptide fragments with bactericidal properties. Two fragments were obtained from the tryptic digestion. One was a pentapeptide with the sequence EQLTK (residues 1-5) and the other, GYGGVSLPEWVCTTF ALCSEK (residues (17-31)S-S(109-114)), was composed of two polypeptide chains held together by a disulfide bridge. Fragmentation of alpha-lactalbumin by chymotrypsin yielded CKDDQNPH ISCDKF (residues (61-68)S-S(75-80)), also a polypeptide composed of two polypeptide chains held together by a disulfide bridge. The three polypeptides were synthesized and found to exert antimicrobial activities. The polypeptides were mostly active against Gram-positive bacteria. Gram-negative bacteria were only poorly susceptible to the bactericidal action of the polypeptides. GYGGVSLPEWVCTTF ALCSEK was most, EQLTK least bactericidal. Replacement of leucine (23) with isoleucine, having a similar chemical structure but higher hydrophobicity, in the sequence GYGGVSLPEWVCTTF ALCSEK significantly reduced the bactericidal capacity of the polypeptide. Digestion of alpha-lactalbumin by pepsin yielded several polypeptide fragments without antibacterial activity. alpha-Lactalbumin in contrast to its polypeptide fragments was not bactericidal against all the bacterial strains tested. Our results suggest a possible antimicrobial function of alpha-lactalbumin after its partial digestion by endopeptidases.
Keywords: [alpha]-Lactalbumin; Antibacterial activity; Antibiotic; Bactericidal peptide
Citation: 2

Milk proteins as precursors of bioactive peptides

Cited Entries: LFB0004, LFB0005, LFB0007, LFB0094, LFB0121, ALA0003, ALA0007, ALA0008

Authors:Dziuba, M., Dziuba, B., Iwaniak, A.
Journal: ACTA Scientiarum Polonorum, Technologia Alimentaria 2009, 8(1).
Abstract: Milk proteins, a source of bioactive peptides, are the subject of numerous research studies aiming to, among others, evaluate their properties as precursors of biologically active peptides. Physiologically active peptides released from their precursors may interact with selected receptors and affect the overall condition and health of humans. By relying on the BIOPEP database of proteins and bioactive peptides, developed by the Department of Food Biochemistry at the University of Warmia and Mazury in Olsztyn (www.uwm.edu.pl/biochemia), the profiles of potential activity of milk proteins were determined and the function of those proteins as bioactive peptide precursors was evaluated based on a quantitative criterion, i.e. the occurrence frequency of bioactive fragments (A). The study revealed that milk proteins are mainly a source of peptides with the following types of activity: antihypertensive (Amax = 0.225), immunomodulating (0.024), smooth muscle contracting (0.011), antioxidative (0.029), dipeptidyl peptidase IV inhibitors (0.148), opioid (0.073), opioid antagonistic (0.053), bonding and transporting metals and metal ions (0.024), antibacterial and antiviral (0.024), and antithrombotic (0.029). The enzymes capable of releasing bioactive peptides from precursor proteins were determined for every type of activity. The results of the experiment indicate that milk proteins such as lactoferrin, α-lactalbumin, β-casein and κ-casein hydrolysed by trypsin can be a relatively abundant source of biologically active peptides.

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