Table 1.

Enzyme engineering towards site-specific immobilization.

Enzyme Engineering	Carrier Type/Site	Mode of Interaction
Genetic engineering of insertion or fusion: Poly-Histidine (6 or more) Peptides/Epitopes: ○ Flag ○ Myc ○ HA ○ Strep ○ LPXTG ○ SNAP * ○ CLIP * ○ HaloTag ○ GEPI ○ SAP Binding domains ○ Chitin ○ Cellulose ○ Maltose ○ PHA ○ DNA Amino acids/functional groups ○ Lysine ○ Cysteine ○ Aspartate ○ Glutamate ○ Poly-Lysine ○ Poly-Aspartate ○ Poly-Glutamate	Immobilized metal ion   ○ Monoclonal antibody ○ Monoclonal antibody ○ Monoclonal antibody ○ Engineered avidin ○ Diglycine-surface ○ Benzylguanine-surface ○ Benzylguanine-surface ○ Chloroalkane-surface ○ Inorganic carrier ○ Carrier-free self-assembly   ○ Chitin ○ Cellulose ○ Maltose-surface ○ PHA ○ DNA   ○ NHS-surface ○ Maleimide-surface ○ Amine-modified surface ○ Amine-modified surface ○ Negatively charged surface ○ Positively charged surface ○ Positively charged surface	Metal coordination   ○ Affinity ○ Affinity ○ Affinity ○ Affinity ○ Covalent ○ Covalent ○ Covalent ○ Covalent ○ Non-covalent ○ Non-covalent   ○ Affinity ○ Affinity ○ Affinity ○ Hydrophobic ○ Watson-Crick base pairs   ○ Covalent ○ Covalent ○ Covalent ○ Covalent ○ Ionic ○ Ionic ○ Ionic
Chemical modifications: Biotinylation DNA	Avidin/streptavidin Complimentary DNA or positive charges	Affinity Watson-Crick base pair or ionic
Enzymatic modifications: Biotin (biotin ligase) Peptides (sortase A) Farnesyl azides or alkynes (PFT) Primary amino-containing probes (TG) Alkyl or aryl azido-lipoic acids (Lpl)	Avidin coated surface Diglycine-functionalized glass “click” chemistry functional group displaying surface DNA displaying surface “click” chemistry functional group displaying surface	Affinity Covalent Covalent Watson-Crick base pairs Covalent

* Self-labelling tags (~20–33 kDa); Flag, peptide with sequence DYKDDDDK; Myc, peptide with sequence EQKLISEEDL; HA, Haemagglutinin; Strep, peptide with sequence WSHPQFEK; LPXTG, sortase recognition motif peptide with sequence LPXTG where X is any amino acid; SNAP, 19.4 kDa polypeptide; CLIP, a modified SNAP; HaloTag, modified haloalkane dehalogenase designed to covalently bind to synthetic ligands; GEPI, genetically modified peptides binding inorganics (there are also natural peptide binding inorganics such as silaffins binding silica); SAP, self-assembling peptides; PHA, polyhydroxyalkanoates; PFT, protein farnesyl transferase; TG, transglutaminase; Lpl, lipoic acid ligase.