Biomaterial Database

Improved adsorption to starch of a beta-galactosidase fusion protein containing the starch-binding domain from Aspergillus glucoamylase. 1991

L J Chen, and C Ford, and A Kusnadi, and Z L Nikolov

Department of Genetics, Iowa State University, Ames 50011.

We have previously shown (Chen et al., 1991) that a beta-galactosidase (beta-gal) fusion protein (BSB133) containing 133 amino acids (aa) from the C-terminus of Aspergillus glucoamylase (GA) adsorbs strongly to starch compared to beta-gal, due to the presence of the GA starch-binding domain. We have now made deletions at the N-terminus of this 133-aa region to test the minimal size required for starch binding of beta-gal fusion proteins. Three fusion proteins (BSB119, BSB103, and BSB80) were genetically engineered, containing 119, 103, and 80 C-terminal aa from GA, respectively. The fusion proteins were expressed in Escherichia coli and purified. Purified BSB119 adsorbed to native starch at least 2-fold more strongly than did BSB133 or fusion proteins with shorter tails. Adsorption isotherms generated over a wide range of initial concentrations indicated a 10-fold difference in the loading capacity of starch for BSB119 (36.5 mg of protein/g of starch) compared to beta-gal (3.7 mg of protein/g of starch). Adsorption constants calculated from the initial slopes of the isotherms indicated a nearly 30-fold difference in affinity to starch for BSB119 (Kad = 63 mL/g of starch) compared to beta-gal (Kad = 2.3 mL/g of starch). BSB119 in the presence of crude enzyme extracts also bound to starch with a high affinity compared to a beta-gal control. Potential applications of the starch-binding tail include enzyme immobilization to starch or recovery and purification of target proteins from crude extracts.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010957	Plasmids	Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.	Episomes,Episome,Plasmid
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011993	Recombinant Fusion Proteins	Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.	Fusion Proteins, Recombinant,Recombinant Chimeric Protein,Recombinant Fusion Protein,Recombinant Hybrid Protein,Chimeric Proteins, Recombinant,Hybrid Proteins, Recombinant,Recombinant Chimeric Proteins,Recombinant Hybrid Proteins,Chimeric Protein, Recombinant,Fusion Protein, Recombinant,Hybrid Protein, Recombinant,Protein, Recombinant Chimeric,Protein, Recombinant Fusion,Protein, Recombinant Hybrid,Proteins, Recombinant Chimeric,Proteins, Recombinant Fusion,Proteins, Recombinant Hybrid
D002872	Chromosome Deletion	Actual loss of portion of a chromosome.	Monosomy, Partial,Partial Monosomy,Deletion, Chromosome,Deletions, Chromosome,Monosomies, Partial,Partial Monosomies
D005087	Glucan 1,4-alpha-Glucosidase	An enzyme that catalyzes the hydrolysis of terminal 1,4-linked alpha-D-glucose residues successively from non-reducing ends of polysaccharide chains with the release of beta-glucose. It is also able to hydrolyze 1,6-alpha-glucosidic bonds when the next bond in sequence is 1,4.	1,4-alpha-Glucosidase, Exo,Amyloglucosidase,Exo-1,4-alpha-Glucosidase,Glucoamylase,gamma-Amylase,Glucoamylase G1,Glucoamylase G2,1,4-alpha-Glucosidase, Glucan,Exo 1,4 alpha Glucosidase,Glucan 1,4 alpha Glucosidase,gamma Amylase
D000327	Adsorption	The adhesion of gases, liquids, or dissolved solids onto a surface. It includes adsorptive phenomena of bacteria and viruses onto surfaces as well. ABSORPTION into the substance may follow but not necessarily.	Adsorptions
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D001230	Aspergillus	A genus of mitosporic fungi containing about 100 species and eleven different teleomorphs in the family Trichocomaceae.
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA