Ace inhibitory peptide composition derived from ginkgo protein and preparation method and application thereof

A preparation method of an ACE inhibitory peptide composition consisting of six small purified peptides with amino acid sequences of GFDGR (SEQ ID NO. 1), NDPGR (SEQ ID NO. 2), LDQTYRP (SEQ ID NO. 3), REHETIIL (SEQ ID NO. 4), LRMPGPPSDDY (SEQ ID NO. 5) and LRMPGPPSDDYER (SEQ ID NO. 6), comprising the following steps:

• (1) preparing defatted ginkgo nut powder by defatting ginkgo nut powder with petroleum ether to obtain the defatted ginkgo nut powder;
• (2) preparing ginkgo protein by:
• firstly, after mixing the defatted ginkgo nut powder obtained in step (1) with water, adding NaOH solution to adjust its pH to 10.0,
• then, extracting at 40-45° C., and
• subsequently, after centrifugation the extract to obtain supernatant, adjusting pH of the supernatant to 4-4.5 with HCl solution, and centrifuging the supernatant after pH adjustment to obtain ginkgo protein powder;
• (3) hydrolyzing ginkgo protein by:
• firstly, preparing the ginkgo protein powder obtained in step (2) into a protein solution with a substrate concentration of 7.17%,
• then, adding NaOH solution into the protein solution to adjust the pH to 7.40, and adding 5% of AS1.398 neutral protease for hydrolysis when the temperature of the reaction reaches 45.6° C.;
• and
• after hydrolysis for 6 h, collecting supernatant after centrifugation to obtain ginkgo protein hydrolysate;
• (4) separating ginkgo protein hydrolysate by:
• ultrafiltering and separating the ginkgo protein hydrolysate obtained in step (3) by an ultrafiltration membrane with a molecular weight cut-off of 3 kDa to obtain ultrafiltration permeate;
• (5) preparing crude ACE inhibitory peptide derived from ginkgo protein by:
• freeze-drying the ultrafiltration permeate obtained in step (4) to obtain crude ACE inhibitory peptide derived from ginkgo protein;
• and
• (6) preparing ACE inhibitory peptide composition derived from ginkgo protein by:
• separating and purifying the crude ACE inhibitory peptide derived from ginkgo protein obtained in step (5) by a reversed-phase chromatographic column, eluting and separating components at the wavelength of 220 nm, and collecting a first component with the strongest ACE inhibitory activity,
• separating and purifying the first component with the strongest ACE inhibitory activity at the wavelength of 220 nm by using a peptide chromatographic column, and collecting a second component with the strongest ACE inhibitory activity, and
• purifying the second component with the strongest ACE inhibitory activity by using a peptide chromatographic column to obtain the ACE inhibitory peptide composition derived from ginkgo protein.