Disclosed is a polypeptide belonging to the avidin-streptavidin family, wherein the polypeptide comprises a D-amino acid residue in 90% or more of amino acid residues among amino acid residues other than glycine of the polypeptide, has a binding ability to L-biotin, and has substantially no binding ability to D-biotin.

Disclosed is a polypeptide belonging to the avidin-streptavidin family, wherein the polypeptide comprises a D-amino acid residue in 90% or more of amino acid residues among amino acid residues other than glycine of the polypeptide, has a binding ability to L-biotin, and has substantially no binding ability to D-biotin.

Provided herein, in some aspects, are polypeptide monomers comprising an angiotensin-converting enzyme 2 (ACE2) ectodomain and an oligomerization domain. Also provided herein are oligomeric complexes comprising ACE2 monomers. Methods of using such to monomers and oligomeric complexes for the diagnosis, prevention, and treatment of viral infections such as the coronavirus are also provided.

Provided herein, in some aspects, are polypeptide monomers comprising an angiotensin-converting enzyme 2 (ACE2) ectodomain and an oligomerization domain. Also provided herein are oligomeric complexes comprising ACE2 monomers. Methods of using such to monomers and oligomeric complexes for the diagnosis, prevention, and treatment of viral infections such as the coronavirus are also provided.

The present invention provides for a polyketide synthase (PKS) capable of synthesizing a 3-hydroxycarboxylic acid or ketone. The present invention also provides for a host cell comprising the PKS and when cultured produces the 3-hydroxycarboxylic acid or ketone.

The present invention provides for a polyketide synthase (PKS) capable of synthesizing a 3-hydroxycarboxylic acid or ketone. The present invention also provides for a host cell comprising the PKS and when cultured produces the 3-hydroxycarboxylic acid or ketone.

Compositions, methods, and systems are provided for fluorescent polymerase enzyme substrates comprising protein shields for improving enzyme photostability in single molecule real time sequencing. Fluorescent polymerase enzyme substrates of the invention have a protein shield between the fluorescent dye moieties and nucleotide moieties of the polymerase enzyme substrate. The polymerase enzyme substrates have a nucleotide component and a dye component, each attached to a protein. The attachments can be covalent. The protein can, for example, prevent the direct interaction of the fluorescent dye moiety with the enzyme when carrying out nucleotide synthesis, preventing photodamage to the enzyme. The polymerase enzyme substrates of the invention can have multiple dyes and multiple nucleotide moieties.

Compositions, methods, and systems are provided for fluorescent polymerase enzyme substrates comprising protein shields for improving enzyme photostability in single molecule real time sequencing. Fluorescent polymerase enzyme substrates of the invention have a protein shield between the fluorescent dye moieties and nucleotide moieties of the polymerase enzyme substrate. The polymerase enzyme substrates have a nucleotide component and a dye component, each attached to a protein. The attachments can be covalent. The protein can, for example, prevent the direct interaction of the fluorescent dye moiety with the enzyme when carrying out nucleotide synthesis, preventing photodamage to the enzyme. The polymerase enzyme substrates of the invention can have multiple dyes and multiple nucleotide moieties.

This disclosure related to a group of peptide derivative Omicsynins with antiviral activity against influenza virus and coronavirus. It also related uses of these derivatives, the chemical formula of the peptide derivative Omicsynins is shown in formula (1):

##STR00001##

TABLE-US-00001 R1—R4 are shown in the following table. NO. substituent1 substituent2 substituent3 R.sub.1 [00002] [00003] [00004]Basic amino-acid side chains including lysine, histidine, citrulline residues, and etc. R.sub.2 [00005] —CH(CH.sub.3).sub.2, —CH(CH.sub.3)CH.sub.2CH.sub.3 —CH.sub.2CH(CH.sub.3).sub.2 Neutral amino-acid side chain including tryptophan, serine, threonine, cysteine residues and etc. R.sub.3 [00006] [00007] [00008][00009]R.sub.3 including tyrosine, lysine, histidine, citrulline residues, and etc. R.sub.4 —CH.sub.2OH —CHO R.sub.4 including —CH.sub.2NH.sub.2, —CH═NH,— CH═NOH, —COOH, —COOR.sub.5 (R.sub.5 represents alkyl groups containing 1-3 carbons), -CONH.sub.2 and etc.

This disclosure related to a group of peptide derivative Omicsynins with antiviral activity against influenza virus and coronavirus. It also related uses of these derivatives, the chemical formula of the peptide derivative Omicsynins is shown in formula (1):

##STR00001##

TABLE-US-00001 R1—R4 are shown in the following table. NO. substituent1 substituent2 substituent3 R.sub.1 [00002] [00003] [00004]Basic amino-acid side chains including lysine, histidine, citrulline residues, and etc. R.sub.2 [00005] —CH(CH.sub.3).sub.2, —CH(CH.sub.3)CH.sub.2CH.sub.3 —CH.sub.2CH(CH.sub.3).sub.2 Neutral amino-acid side chain including tryptophan, serine, threonine, cysteine residues and etc. R.sub.3 [00006] [00007] [00008][00009]R.sub.3 including tyrosine, lysine, histidine, citrulline residues, and etc. R.sub.4 —CH.sub.2OH —CHO R.sub.4 including —CH.sub.2NH.sub.2, —CH═NH,— CH═NOH, —COOH, —COOR.sub.5 (R.sub.5 represents alkyl groups containing 1-3 carbons), -CONH.sub.2 and etc.