P450-Modified Ribosomally Synthesized Peptides with Aromatic Cross-Links.

Cyclization of linear peptides is an effective strategy to convert flexible molecules into rigid compounds, which is of great significance for enhancing the peptide stability and bioactivity. Despite significant advances in the past few decades, Nature and chemists' ability to macrocyclize linear peptides is still quite limited. P450 enzymes have been reported to catalyze macrocyclization of peptides through cross-linkers between aromatic amino acids with only three examples. Herein, we developed an efficient workflow for the identification of P450-modified RiPPs in bacterial genomes, resulting in the discovery of a large number of P450-modified RiPP gene clusters. Combined with subsequent expression and structural characterization of the products, we have identified 11 novel P450-modified RiPPs with different cross-linking patterns from four distinct classes. Our results greatly expand the structural diversity of P450-modified RiPPs and provide new insights and enzymatic tools for the production of cyclic peptides.

Amycolamycins A and B, Two Enediyne-Derived Compounds from a Locust-Associated Actinomycete.

Two novel enediyne-derived natural products, amycolamycins A and B (1 and 2), were characterized from a locust-associated actinomycete Amycolatopsis sp. HCa4. Amycolamycins A and B contain a unique 2-(cyclopenta[a]inden-5-yl)oxirane core with suspected enediyne polyketide biosynthetic origin. Sequencing and analysis of the acm biosynthetic gene cluster allowed us to propose the biosynthetic pathway of 1 and 2. Moreover, amycolamycin A (1) was selectively cytotoxic to the M231 breast cancer cell line.

catena-Poly[[chlorido(1,10-phenanthro-line)copper(II)]-µ-{2-[(1S,3S)-3-acetyl-2,2-dimethyl-cyclo-but-yl]acetato}].

The title compound, [Cu(C(10)H(15)O(3))Cl(C(12)H(8)N(2))](n), is a one-dimensional coordination polymer. The Cu(II) atom is coordin-ated by a chloride ion, two N atoms from the 1,10-phenanthroline ligand, and a monodentate carboxyl-ate O atom from the pinononate anion, forming a CuN(2)ClO approximate square plane. A symmetry-generated pinononate O atom completes a square-based pyramidal geometry for the copper ion. The bridging 2-(3-acetyl-2,2-dimethyl-cyclo-but-yl)acetate anion leads to chains in the crystal propagating in [001]. Adjacent 1,10-phenanthroline rings form a dihedral angle of 39.4 (2)°.

Chlorido(5-formyl-2-hydroxy-phenyl-κC)mercury(II).

In the planar (r.m.s. deviation = 0.027 Å) title compound, [Hg(C(7)H(5)O(2))Cl], the Hg(II) atom shows a typical linear coordination by a C atom of the benzene ring and a Cl atom. Inter-molecular O-H⋯O hydrogen bonds are present in the crystal structure, resulting in chains propagating along the b axis. The crystal studied was a non-merohedral twin, with a twin ratio of 0.802 (2):0.198 (2).

(2E,5E)-2,5-Difurfurylidenecyclo-penta-none.

In the title mol-ecule, C(15)H(12)O(3), the three five-membered rings are nearly coplanar: the dihedral angles between the cyclopentanone ring and the furan rings are 3.5 (2) and 9.7 (2)°, and the two furan rings form a dihedral angle of 7.2 (2)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds help to consolidate the crystal packing.

(2E,6E)-2,6-Difurfurylidenecyclo-hexa-none.

The complete mol-ecule of the title compound, C(16)H(14)O(3), is generated by crystallographic mirror symmetry, with two C atoms and one O atom lying on the mirror plane. The mol-ecule adopts an E configuration about the C=C bond and the dihedral angle between the furan rings is 16.1 (2)°.

Sodium (1R,2S,5S)-2-hydr-oxy-6,6-dimethyl-bicyclo-[3.1.1]heptane-2-carboxyl-ate penta-hydrate.

In the title compound, Na(+)·C(10)H(15)O(3) (-)·5H(2)O, the vertices of a distorted octa-hedron centred on the Na(+) cation are defined by six O atoms of water mol-ecules. The edge-sharing Na(H(2)O)(6) octa-hedra form a chain extended along the b-axis direction with adjacent Na(+) cations related by a twofold screw symmetry operation. The organic anion, which is not in close contact with the Na(+ )cation, is hydrogen-bonded to an uncoordinated water mol-ecule and to water mol-ecules of the Na(H(2)O)(6) octa-hedra.