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Title: Replacement of the Distal Histidine Reveals a Noncanonical Heme Binding Site in a 2-on-2 Hemoglobin
Award ID(s):
1330488
PAR ID:
10106994
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Biochemistry
Volume:
57
Issue:
40
ISSN:
0006-2960
Page Range / eLocation ID:
5785 to 5796
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  1. ABSTRACT In 1956, Tutte proved the celebrated theorem that every 4‐connected planar graph is Hamiltonian. This result implies that every more than ‐tough planar graph on at least three vertices is Hamiltonian and so has a 2‐factor. Owens in 1999 constructed non‐Hamiltonian maximal planar graphs of toughness arbitrarily close to and asked whether there exists a maximal non‐Hamiltonian planar graph of toughness exactly . In fact, the graphs Owens constructed do not even contain a 2‐factor. Thus the toughness of exactly is the only case left in asking the existence of 2‐factors in tough planar graphs. This question was also asked by Bauer, Broersma, and Schmeichel in a survey. In this paper, we close this gap by constructing a maximal ‐tough plane graph with no 2‐factor, answering the question asked by Owens as well as by Bauer, Broersma, and Schmeichel. 
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