A method of characterising a target polynucleotide, comprising: (a) contacting the target polynucleotide with a transmembrane pore and a construct comprising a helicase and an additional polynucleotide binding moiety, wherein the helicase is attached to the polynucleotide binding moiety and the construct has the ability to control the movement of a polynucleotide, such that the construct controls the movement of the target polynucleotide through the pore; and (b) taking one or more measurements as the polynucleotide moves with respect to the pore wherein the measurements are indicative of one or more characteristics of the target polynucleotide and thereby characterising the target polynucleotide; wherein: (i) the polynucleotide binding moiety comprises one or more helicases, wherein: (a) the two or more helicases in the construct are different from one another; or (b) the two or more helicases are the same or similar; or (c) the two or more helicases are the same or similar and are attached using the same amino acid residue in each helicase; or (ii) the polynucleotide binding moiety (a) comprises one or more domains independently selected from helix-hairpin-helix (HhH) domains, eukaryotic single-stranded binding proteins (SSBs), bacterial SSBs, archaeal SSBs, viral SSBs, double-stranded binding proteins, sliding clamps, processivity factors, DNA binding loops, replication initiation proteins, telomere binding proteins, repressors, zinc fingers and proliferating cell nuclear antigens (PCNAs) or the polynucleotide binding moiety is selected from those shown in Table 4 and variants thereof; or (b) is derived from (a) an exonuclease, polymerase or topoisomerase or (b) Phi29 polymerase (SEQ ID NO: 62) or a variant thereof. (a) contacting the target polynucleotide with a transmembrane pore and a construct comprising a helicase and an additional polynucleotide binding moiety, wherein the helicase is attached to the polynucleotide binding moiety and the construct has the ability to control the movement of a polynucleotide, such that the construct controls the movement of the target polynucleotide through the pore; and (b) taking one or more measurements as the polynucleotide moves with respect to the pore wherein the measurements are indicative of one or more characteristics of the target polynucleotide and thereby characterising the target polynucleotide; wherein: (i) the polynucleotide binding moiety comprises one or more helicases, wherein: (a) the two or more helicases in the construct are different from one another; or (b) the two or more helicases are the same or similar; or (c) the two or more helicases are the same or similar and are attached using the same amino acid residue in each helicase; or (ii) the polynucleotide binding moiety (a) comprises one or more domains independently selected from helix-hairpin-helix (HhH) domains, eukaryotic single-stranded binding proteins (SSBs), bacterial SSBs, archaeal SSBs, viral SSBs, double-stranded binding proteins, sliding clamps, processivity factors, DNA binding loops, replication initiation proteins, telomere binding proteins, repressors, zinc fingers and proliferating cell nuclear antigens (PCNAs) or the polynucleotide binding moiety is selected from those shown in Table 4 and variants thereof; or (b) is derived from (a) an exonuclease, polymerase or topoisomerase or (b) Phi29 polymerase (SEQ ID NO: 62) or a variant thereof. (i) the polynucleotide binding moiety comprises one or more helicases, wherein: (a) the two or more helicases in the construct are different from one another; or (b) the two or more helicases are the same or similar; or (c) the two or more helicases are the same or similar and are attached using the same amino acid residue in each helicase; or (a) the two or more helicases in the construct are different from one another; or (b) the two or more helicases are the same or similar; or (c) the two or more helicases are the same or similar and are attached using the same amino acid residue in each helicase; or (ii) the polynucleotide binding moiety (a) comprises one or more domains independently selected from helix-hairpin-helix (HhH) domains, eukaryotic single-stranded binding proteins (SSBs), bacterial SSBs, archaeal SSBs, viral SSBs, double-stranded binding proteins, sliding clamps, processivity factors, DNA binding loops, replication initiation proteins, telomere binding proteins, repressors, zinc fingers and proliferating cell nuclear antigens (PCNAs) or the polynucleotide binding moiety is selected from those shown in Table 4 and variants thereof; or (b) is derived from (a) an exonuclease, polymerase or topoisomerase or (b) Phi29 polymerase (SEQ ID NO: 62) or a variant thereof.