A compound having the structure of Formula, or a pharmaceutically acceptable salt thereof: wherein: R 1, R 2, R 3, R 4, R 5, R 6, R 7, R 8, R 15, and R 16 are each independently selected from hydrogen, C 1 -C 6 alkyl, C 1 -C 6 alkylene-COOH, sulfonate, -COOH, -SO 2 -NH 2, or C 1 -C 6 alkoxy; R 9 is sulfonate; L 1 is C 3 -C 6 alkylene; L 2 is C 1 -C 10 alkylene; L 3 is a bond, -O-, -NR 10 -, -NR 10 -C 1 -C 6 alkylene-, -O-NR 10 -, -NR 10 -C 1 -C 6 alkylene- (O-C 1 -C 6 alkylene) n -, -NR 10 -L 4 -, -NR 10 -C 1 -C 6 alkylene-NR 11 - (C (= O) -C 1 -C 6 alkylene-O-) m -, or -NR 10 -C 1 -C 6 alkylene--NR 10 -C 1 -C 6 alkylene--NR 10 -C 1 -C 6 alkylene-; L 4 is a bond, -heterocyclyl-, or -heterocyclyl-C 1 -C 6 alkylene-; R 10 is hydrogen or C 1 -C 6 alkyl; R 11 is hydrogen or C 1 -C 6 alkyl; R 12 and R 13 are independently selected from hydrogen, C 1 -C 6 alkyl, or R 12 and R 13 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring; R 14 is hydrogen or C 1 -C 6 alkylene, -(L 5)-aryl, -(L 5)-heteroaryl, -NR 17 R 18, R 14 and R 19 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring, or R 14 and R 20 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring; L 5 is a bond, C 1 -C 10 alkylene, -O-, or -NR 10 -; R 17 and R 18 are each independently hydrogen or aryl; R 19 and R 20 are independently selected from hydrogen, C 1 -C 6 alkyl, R 14 and R 19 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring, or R 14 and R 20 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring; n is 0, 1, 2, or 3; m is 0, 1, 2, or 3; p is 0, 1, 2, or 3; q is 0, 1, 2, or 3; and A 4 is a polypeptide having at least 90% sequence identity with SEQ ID NO: 9 or a fragment thereof, wherein the fragment of A 4 comprises at least 25 amino acid residues. R 1, R 2, R 3, R 4, R 5, R 6, R 7, R 8, R 15, and R 16 are each independently selected from hydrogen, C 1 -C 6 alkyl, C 1 -C 6 alkylene-COOH, sulfonate, -COOH, -SO 2 -NH 2, or C 1 -C 6 alkoxy; R 9 is sulfonate; L 1 is C 3 -C 6 alkylene; L 2 is C 1 -C 10 alkylene; L 3 is a bond, -O-, -NR 10 -, -NR 10 -C 1 -C 6 alkylene-, -O-NR 10 -, -NR 10 -C 1 -C 6 alkylene- (O-C 1 -C 6 alkylene) n -, -NR 10 -L 4 -, -NR 10 -C 1 -C 6 alkylene-NR 11 - (C (= O) -C 1 -C 6 alkylene-O-) m -, or -NR 10 -C 1 -C 6 alkylene--NR 10 -C 1 -C 6 alkylene--NR 10 -C 1 -C 6 alkylene-; L 4 is a bond, -heterocyclyl-, or -heterocyclyl-C 1 -C 6 alkylene-; R 10 is hydrogen or C 1 -C 6 alkyl; R 11 is hydrogen or C 1 -C 6 alkyl; R 12 and R 13 are independently selected from hydrogen, C 1 -C 6 alkyl, or R 12 and R 13 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring; R 14 is hydrogen or C 1 -C 6 alkylene, -(L 5)-aryl, -(L 5)-heteroaryl, -NR 17 R 18, R 14 and R 19 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring, or R 14 and R 20 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring; L 5 is a bond, C 1 -C 10 alkylene, -O-, or -NR 10 -; R 17 and R 18 are each independently hydrogen or aryl; R 19 and R 20 are independently selected from hydrogen, C 1 -C 6 alkyl, R 14 and R 19 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring, or R 14 and R 20 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring; n is 0, 1, 2, or 3; m is 0, 1, 2, or 3; p is 0, 1, 2, or 3; q is 0, 1, 2, or 3; and A 4 is a polypeptide having at least 90% sequence identity with SEQ ID NO: 9 or a fragment thereof, wherein the fragment of A 4 comprises at least 25 amino acid residues.